Search Results

Search found 13625 results on 545 pages for 'apache math'.

Page 413/545 | < Previous Page | 409 410 411 412 413 414 415 416 417 418 419 420  | Next Page >

  • Having Hotlink Protectin problem in nginx

    - by Ayaz Malik
    Hello, i am having image hotlink protection problem in my nginx need help. i have a huge issue of my site's images being submited to social networks like stumbleupon with direct link ... xxxxx.jpg which some times get huge traffic and increases cpu usage plus bandwidth usage. what i am trying to do is block direct access to image from other refrers and hotlink protection. Here is the code from my vhost.conf server { access_log off; error_log logs/vhost-error_log warn; listen 80; server_name mydomain.com www.mydomain.com; # uncomment location below to make nginx serve static files instead of Apache # NOTE this will cause issues with bandwidth accounting as files wont be logged location ~* \.(gif|jpg|jpeg|png|wmv|avi|mpg|mpeg|mp4|htm|html|js|css)$ { root /home/username/public_html; expires 1d; } root /home/mydomain/public_html; } location / { client_max_body_size 10m; client_body_buffer_size 128k; proxy_send_timeout 90; proxy_read_timeout 90; proxy_buffer_size 4k; # you can increase proxy_buffers here to suppress "an upstream response # is buffered to a temporary file" warning proxy_buffers 16 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; proxy_connect_timeout 30s; proxy_redirect http://www.mydomain.com:81 http://www.mydomain.com; proxy_redirect http://mydomain.com:81 http://mydomain.com; proxy_pass http://ip_address/; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; expires 24h; } } So for hotlink protection i added this code : location ~* (\.jpg|\.png|\.gif|\.jpeg)$ { valid_referers blocked www.mydomain.com mydomain.com; if ($invalid_referer) { return 403; } This is how the current nginx code for this domain looks like but didn't worked: server { access_log off; error_log logs/vhost-error_log warn; listen 80; server_name mydomain.com www.mydomain.com; # uncomment location below to make nginx serve static files instead of Apache # NOTE this will cause issues with bandwidth accounting as files wont be logged location ~* \.(gif|jpg|jpeg|png|wmv|avi|mpg|mpeg|mp4|htm|html|js|css)$ { root /home/username/public_html; expires 1d; } root /home/mydomain/public_html; } location ~* (\.jpg|\.png|\.gif|\.jpeg)$ { valid_referers blocked www.mydomain.com mydomain.com; if ($invalid_referer) { return 403; } location / { client_max_body_size 10m; client_body_buffer_size 128k; proxy_send_timeout 90; proxy_read_timeout 90; proxy_buffer_size 4k; # you can increase proxy_buffers here to suppress "an upstream response # is buffered to a temporary file" warning proxy_buffers 16 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; proxy_connect_timeout 30s; proxy_redirect http://www.mydomain.com:81 http://www.mydomain.com; proxy_redirect http://mydomain.com:81 http://mydomain.com; proxy_pass http://ip_address/; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; expires 24h; } } Thank you in advance :) cheers

    Read the article

  • Routing not working correctly using the laravel framework

    - by samayres1992
    I'm using the book wrote by one of the guys that created laravel, so I'd like to think for the most part this code isn't horribly wrong. My server is setup with nginx serving all static files and apache2 serving php. My config for each are the following: apache2: <VirtualHost *> # Host that will serve this project. ServerName litl.it # The location of our projects public directory. DocumentRoot /var/www/litl.it/laravel/public # Useful logs for debug. CustomLog /var/log/apache.access.log common ErrorLog /var/log/apache.error.log # Rewrites for pretty URLs, better not to rely on .htaccess. <Directory /var/www/litl.it/laravel/public> <IfModule mod_rewrite.c> Options -MultiViews RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^ index.php [L] </IfModule> </Directory> nginx: server { # Port that the web server will listen on. listen 80; # Host that will serve this project. server_name litl.it *.litl.it; # Useful logs for debug. access_log /var/log/nginx.access.log; error_log /var/log/nginx.error.log; rewrite_log on; # The location of our projects public directory. root /var/www/litl.it/laravel/public; # Point index to the Laravel front controller. index index.php; location / { # URLs to attempt, including pretty ones. try_files $uri $uri/ /index.php?$query_string; } # Remove trailing slash to please routing system. if (!-d $request_filename) { rewrite ^/(.+)/$ /$1 permanent; } # PHP FPM configuration. location ~* \.php$ { proxy_pass http://127.0.0.1:8080; include /etc/nginx/proxy_params; try_files index index.php $uri =404; include /etc/nginx/fastcgi_params; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root/php/$fastcgi_script_name; } # We don't need .ht files with nginx. location ~ /\.ht { deny all; } location @proxy { proxy_pass http://127.0.0.1:8080; include /etc/nginx/proxy_params; } error_page 403 /error/403.html; error_page 404 /error/404.html; error_page 405 /error/405.html; error_page 500 501 502 503 504 /error/5xx.html; location ^~ /error/ { internal; root /var/www/litl.it/lavarel/public/error; } } I'm including these server configs, as I feel this maybe the issue? Here is my incredibly basic routing file that should return "routing is working" on domain.com/test but instead it just returns the homepage. <?php Route::get('/', function() { return View::make('hello'); }); Route::get('/test', function() { return "routing is working"; }); Any ideas where I'm going wrong, I'm following this tutorial very closely and I'm confused why there is issue. Thanks!

    Read the article

  • Centos 7. Freeradius fails to start on boot

    - by Alex
    I was messing around with FreeRADIUS and MySQL (MariaDB) and it seems FreeRADIUS service can't start properly on startup. But it starts fine using root user or in debug mode (radiusd -X) and works just fine! Debug mode shows no errors. systemctl command shows that radiusd.service has failed to start. /var/log/messages output: Aug 21 15:52:29 nexus-test systemd: Starting The Apache HTTP Server... Aug 21 15:52:29 nexus-test systemd: Starting MariaDB database server... Aug 21 15:52:29 nexus-test systemd: Starting FreeRADIUS high performance RADIUS server.... Aug 21 15:52:29 nexus-test systemd: Started OpenSSH server daemon. Aug 21 15:52:29 nexus-test mysqld_safe: 140821 15:52:29 mysqld_safe Logging to '/var/log/mariadb/mariadb.log'. Aug 21 15:52:29 nexus-test mysqld_safe: 140821 15:52:29 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql Aug 21 15:52:30 nexus-test systemd: Started Postfix Mail Transport Agent. Aug 21 15:52:30 nexus-test avahi-daemon[604]: Registering new address record for fe80::250:56ff:fe85:e4af on eth0.*. Aug 21 15:52:30 nexus-test systemd: radiusd.service: control process exited, code=exited status=1 Aug 21 15:52:30 nexus-test systemd: Failed to start FreeRADIUS high performance RADIUS server.. Aug 21 15:52:30 nexus-test systemd: Unit radiusd.service entered failed state. Aug 21 15:52:31 nexus-test kdumpctl: kexec: loaded kdump kernel Aug 21 15:52:31 nexus-test kdumpctl: Starting kdump: [OK] Aug 21 15:52:31 nexus-test systemd: Started Crash recovery kernel arming. Aug 21 15:52:31 nexus-test systemd: Started The Apache HTTP Server. Aug 21 15:52:31 nexus-test systemd: Started MariaDB database server. /var/log/radius/radius.log output: Thu Aug 21 15:24:16 2014 : Info: rlm_sql (sql): Driver rlm_sql_mysql (module rlm_sql_mysql) loaded and linked Thu Aug 21 15:24:16 2014 : Info: rlm_sql (sql): Attempting to connect to database "radius" Thu Aug 21 15:24:16 2014 : Info: rlm_sql (sql): Opening additional connection (0) Thu Aug 21 15:24:16 2014 : Error: rlm_sql_mysql: Couldn't connect socket to MySQL server radius@localhost:radius Thu Aug 21 15:24:16 2014 : Error: rlm_sql_mysql: Mysql error 'Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)' Thu Aug 21 15:24:16 2014 : Error: rlm_sql (sql): Opening connection failed (0) Thu Aug 21 15:24:16 2014 : Error: /etc/raddb/mods-enabled/sql[47]: Instantiation failed for module "sql" After seeing this I tried to replicate the problem, killed mariadb.service and started to run debug mode again. And it spits out the same problem as in the radius.log. I tried disabling iptables and firewalld and rebooting, but no luck: systemctl disable iptables systemctl disable firewalld So maybe the problem is in the process startup order or delay of some kind. Maybe FreeRADIUS's SQL module can't connect to not yet started MariaDB? If it, how can I fix this? In earlier versions of RHEL/CENTOS I know you easily see service start order in like rc.d or stuff, now IDK. I am new to this fancy "systemd", "systemctl", "firewalld" stuff Centos 7 introduced so sorry I'm a little bit confused. Also this new FreeRADIUS 3 structure... PS. MariaDB is enabled on startup, credentials in FR DB configuration are correct A little update: cat /etc/systemd/system/multi-user.target.wants/radiusd.service output: [Unit] Description=FreeRADIUS high performance RADIUS server. After=syslog.target network.target [Service] Type=forking PIDFile=/var/run/radiusd/radiusd.pid ExecStartPre=-/bin/chown -R radiusd.radiusd /var/run/radiusd ExecStartPre=/usr/sbin/radiusd -C ExecStart=/usr/sbin/radiusd -d /etc/raddb ExecReload=/usr/sbin/radiusd -C ExecReload=/bin/kill -HUP $MAINPID [Install] WantedBy=multi-user.target

    Read the article

  • Outlook Web Access, reverse proxy and browser

    - by M'vy
    Hi SF'ers! We recently moved an exchange server behind a reverse proxy due to the loss of a public IP. I've managed to configure the reverse proxy (httpd proxy_http). But there is a problem for the SSL configuration. When accessing the OWA interface with Firefox, all is ok and working. When accessing with MSIE or Chrome, they do not retrieve the good SSL Certificate. I think this is due to the multiples virtual host for httpd. Is there a workaround to make sure MSIE/Chrome request the certificate for the good domain name like FF does? Already tested with the SSL virtual host : SetEnvIf User-Agent ".*MSIE.*" value BrowserMSIE Header unset WWW-Authenticate Header add WWW-Authenticate "Basic realm=exchange.domain.com" A: ProxyPreserveHost On also: BrowserMatch ".*MSIE.*" \ nokeepalive ssl-unclean-shutdown \ downgrade-1.0 force-response-1.0 Or: SetEnvIf User-Agent ".*MSIE.*" \ nokeepalive ssl-unclean-shutdown \ downgrade-1.0 force-response-1.0 And lots of ProxyPassand ProxyReversePath on /exchweb /exchange /public etc... And it still don't seem to work. Any clue? Thanks. Edit 1: Precision of versions # openssl version OpenSSL 0.9.8k-fips 25 Mar 2009 /usr/sbin/httpd -v Server version: Apache/2.2.11 (Unix) Server built: Mar 17 2009 09:15:10 Browser versions : MSIE : 8.0.6001 Opera: Version 11.01 Revision 1190 Firefox: 3.6.15 Chrome: 10.0.648.151 Operating System: Windows Vista 32bits. They are all SNI compliant, I've tested them this afternoon https://sni.velox.ch/ You're right Shane Madden, I have multiple sites on the same public IP (and same port as well). The server itself is just a reverse proxy, that rewrite addresses to internal servers. The default host is a dev site, configure with the certificate that does not match the OWA (of course... would have been to easy) <VirtualHost *:443> ServerName dev2.domain.com ServerAdmin [email protected] CustomLog "| /usr/sbin/rotatelogs /var/log/httpd/access-%y%m%d.log 86400" combined ErrorLog "| /usr/sbin/rotatelogs /var/log/httpd/error-%y%m%d.log 86400" LogLevel warn RewriteEngine on SetEnvIfNoCase X-Forwarded-For .+ proxy=yes SSLEngine on SSLProtocol -all +SSLv3 +TLSv1 SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP:+eNULL:+SSLv3 SSLCertificateFile /etc/httpd/ssl/domain.com.crt SSLCertificateKeyFile /etc/httpd/ssl/domain.com.key RewriteCond %{HTTP_HOST} dev2\.domain\.com RewriteRule ^/(.*)$ http://dev2.domain.com/$1 [L,P] </VirtualHost> The certificate of domain is a *.domain.com The second vHost is : <VirtualHost *:443> ServerName exchange.domain2.com ServerAdmin [email protected] CustomLog "| /usr/sbin/rotatelogs /var/log/httpd/exchange/access-%y%m%d.log 86400" combined ErrorLog "| /usr/sbin/rotatelogs /var/log/httpd/exchange/error-%y%m%d.log 86400" LogLevel warn SSLEngine on SSLProxyEngine On SSLProtocol -all +SSLv3 +TLSv1 SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP:+eNULL:+SSLv3 SSLCertificateFile /etc/httpd/ssl/exchange.pem SSLCertificateKeyFile /etc/httpd/ssl/exchange.key RewriteEngine on SetEnvIfNoCase X-Forwarded-For .+ proxy=yes RewriteCond %{HTTP_HOST} exchange\.domain2\.com RewriteRule ^/(.*)$ https://exchange.domain2.com/$1 [L,P] </VirtualHost> and it's certificate is exchange.domain2.com only. I presume the SNI is somewhere not activated on my server. The versions of openssl and apache seams to be ok for the SNI support. The only thing I do not know is if httpd has been compile with the good options. (I assume it's a fedora packet).

    Read the article

  • Trouble in Nginx hotlink protection

    - by Ayaz Malik
    I am trying to implement image hotlink protection problem in nginx and I need help. I have a huge issue of my site's images being submitted to social networks like StumbleUpon with a direct link like http://example.com/xxxxx.jpg Which sometimes gets huge traffic and increases CPU usage and bandwidth usage. I want to block direct access to my images from other referrers and protect them from being hotlinked. Here is the code from my vhost.conf server { access_log off; error_log logs/vhost-error_log warn; listen 80; server_name mydomain.com www.mydomain.com; # uncomment location below to make nginx serve static files instead of Apache # NOTE this will cause issues with bandwidth accounting as files wont be logged location ~* \.(gif|jpg|jpeg|png|wmv|avi|mpg|mpeg|mp4|htm|html|js|css)$ { root /home/username/public_html; expires 1d; } root /home/mydomain/public_html; } location / { client_max_body_size 10m; client_body_buffer_size 128k; proxy_send_timeout 90; proxy_read_timeout 90; proxy_buffer_size 4k; # you can increase proxy_buffers here to suppress "an upstream response # is buffered to a temporary file" warning proxy_buffers 16 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; proxy_connect_timeout 30s; proxy_redirect http://www.mydomain.com:81 http://www.mydomain.com; proxy_redirect http://mydomain.com:81 http://mydomain.com; proxy_pass http://ip_address/; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; expires 24h; } } For hotlink protection I added this code location ~* (\.jpg|\.png|\.gif|\.jpeg)$ { valid_referers blocked www.mydomain.com mydomain.com; if ($invalid_referer) { return 403; } This is the current nginx code for this domain, but it didn't work: server { access_log off; error_log logs/vhost-error_log warn; listen 80; server_name mydomain.com www.mydomain.com; # uncomment location below to make nginx serve static files instead of Apache # NOTE this will cause issues with bandwidth accounting as files wont be logged location ~* \.(gif|jpg|jpeg|png|wmv|avi|mpg|mpeg|mp4|htm|html|js|css)$ { root /home/username/public_html; expires 1d; } root /home/mydomain/public_html; } location ~* (\.jpg|\.png|\.gif|\.jpeg)$ { valid_referers blocked www.mydomain.com mydomain.com; if ($invalid_referer) { return 403; } location / { client_max_body_size 10m; client_body_buffer_size 128k; proxy_send_timeout 90; proxy_read_timeout 90; proxy_buffer_size 4k; # you can increase proxy_buffers here to suppress "an upstream response # is buffered to a temporary file" warning proxy_buffers 16 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; proxy_connect_timeout 30s; proxy_redirect http://www.mydomain.com:81 http://www.mydomain.com; proxy_redirect http://mydomain.com:81 http://mydomain.com; proxy_pass http://ip_address/; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; expires 24h; } } How can I fix this?

    Read the article

  • phpMyAdmin setup issues

    - by EquinoX
    I am trying to follow the tutorial here to setup the user and pass. It says there that "this section is only applicable if your MySQL server is running with --skip-show-database". First question is, how do I check if MySQl server is running with --skip-show-database? Is there any way I can access phpMyAdmin SQL query window without logging in? Otherwise I'd have to execute this SQL from command line. I am also getting this: Cannot load mcrypt extension. Please check your PHP configuration. I have added mcrypt.so to php.ini and doing the following command proves that I have it. [root@DT html]# rpm -qa | grep mcrypt mcrypt-2.6.8-1.el5 php-mcrypt-5.3.5-1.1.w5 libmcrypt-2.5.8-4.el5.centos [root@DT html]# php -v PHP 5.3.5 (cli) (built: Feb 19 2011 13:10:09) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies Now when I go to phpinfo() and search for mcrypt it can find it inside the Configure Command row ('--with-mcrypt=shared,/usr'). So, what to do next?. UPDATE: I didn't put extension=mcrypt.so in php.ini as it will complain the following: PHP Warning: Module 'mcrypt' already loaded in Unknown on line 0 Here's my nginx.conf: #user nobody; worker_processes 2; #error_log logs/error.log; #error_log logs/error.log notice; #error_log logs/error.log info; #pid logs/nginx.pid; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; #log_format main '$remote_addr - $remote_user [$time_local] "$request" ' # '$status $body_bytes_sent "$http_referer" ' # '"$http_user_agent" "$http_x_forwarded_for"'; #access_log logs/access.log main; sendfile on; #tcp_nopush on; #keepalive_timeout 0; keepalive_timeout 65; gzip on; server { listen 80; root /usr/share/nginx/html; server_name localhost; #charset koi8-r; #access_log logs/host.access.log main; location / { #root html; index index.html index.htm; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { #root html; } # proxy the PHP scripts to Apache listening on 127.0.0.1:80 # #location ~ \.php$ { # proxy_pass http://127.0.0.1; #} # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000 # location ~ \.php$ { #root /usr/local/nginx/html; fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME /usr/share/nginx/html$fastcgi_script _name; include fastcgi_params; } # deny access to .htaccess files, if Apache's document root # concurs with nginx's one location ~ /\.ht { deny all; } } # another virtual host using mix of IP-, name-, and port-based configuration # #server { # listen 8000; # listen somename:8080; # server_name somename alias another.alias; # location / { # root html; # index index.html index.htm; # } #} # HTTPS server # #server { # listen 443; # server_name localhost; # ssl on; # ssl_certificate cert.pem; # ssl_certificate_key cert.key; # ssl_session_timeout 5m; # ssl_protocols SSLv2 SSLv3 TLSv1; # ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP; # ssl_prefer_server_ciphers on; # location / { # root html; # index index.html index.htm; # } #} }

    Read the article

  • can't access nginx server from IP

    - by EquinoX
    So 2 days ago I can see that page where it saya "Welcome to nginx", however as of now when I tried to access it, it says 404 page not found... Why is this? Inside my sites-enabled folder I have a file named default and it has the following: # You may add here your # server { # ... # } # statements for each of your virtual hosts server { listen 80; server_name 127.0.0.1; access_log /var/log/nginx/localhost.access.log; location / { root /var/www/nginx-default; index index.html index.htm; } location /doc { root /usr/share; autoindex on; allow 127.0.0.1; deny all; } location /images { root /usr/share; autoindex on; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # #error_page 500 502 503 504 /50x.html; #location = /50x.html { # root /var/www/nginx-default; #} # proxy the PHP scripts to Apache listening on 127.0.0.1:80 # #location ~ \.php$ { #proxy_pass http://127.0.0.1; #} # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000 # location ~ \.php$ { fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME /var/www/nginx-default$fastcgi_script_name; include fastcgi_params; } # deny access to .htaccess files, if Apache's document root # concurs with nginx's one # location ~ /\.ht { deny all; } } # another virtual host using mix of IP-, name-, and port-based configuration # #server { #listen 8000; #listen somename:8080; #server_name somename alias another.alias; #location / { #root html; #index index.html index.htm; #} #} # HTTPS server # #server { #listen 443; #server_name localhost; #ssl on; #ssl_certificate cert.pem; #ssl_certificate_key cert.key; #ssl_session_timeout 5m; #ssl_protocols SSLv2 SSLv3 TLSv1; #ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP; #ssl_prefer_server_ciphers on; #location / { #root html; #index index.html index.htm; #} #} Here's my nginx.conf file: user www-data; worker_processes 4; error_log /var/log/nginx/error.log; pid /var/run/nginx.pid; events { worker_connections 1024; # multi_accept on; } http { include /etc/nginx/mime.types; access_log /var/log/nginx/access.log; sendfile on; #tcp_nopush on; #keepalive_timeout 0; keepalive_timeout 65; tcp_nodelay on; gzip on; gzip_disable "MSIE [1-6]\.(?!.*SV1)"; include /etc/nginx/conf.d/*.conf; include /etc/nginx/sites-enabled/*; } # mail { # # See sample authentication script at: # # http://wiki.nginx.org/NginxImapAuthenticateWithApachePhpScript # # # auth_http localhost/auth.php; # # pop3_capabilities "TOP" "USER"; # # imap_capabilities "IMAP4rev1" "UIDPLUS"; # # server { # listen localhost:110; # protocol pop3; # proxy on; # } # # server { # listen localhost:143; # protocol imap; # proxy on; # } # } What am I doing wrong here? I have other virtual host setup in the sites-enabled as well... UPDATE: The server_name directives are: -admin.api.frapi -api.frapi -default -example.com -php.example.com

    Read the article

  • Configuring nginx server to handle requests from multiple domains

    - by KillABug
    Use Case:- I am working on a web application which allows to create HTML templates and publish them on amazon S3.Now to publish the websites I use nginx as a proxy server. What the proxy server does is,when a user enters the website URL,I want to identify how to check if the request comes from my application i.e app.mysite.com(This won't change) and route it to apache for regular access,if its coming from some other domain like a regular URL www.mysite.com(This needs to be handled dynamically.Can be random) it goes to the S3 bucket that hosts the template. My current configuration is: user nginx; worker_processes 1; error_log /var/log/nginx/error.log; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include /etc/nginx/mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log /var/log/nginx/access.log main; charset utf-8; keepalive_timeout 65; server_tokens off; sendfile on; tcp_nopush on; tcp_nodelay off; Default Server Block to catch undefined host names server { listen 80; server_name app.mysite.com; access_log off; error_log off; location / { proxy_pass http://127.0.0.1:8080; proxy_set_header X-Real-IP $remote_addr; proxy_set_header Host $host; proxy_redirect off; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_connect_timeout 90; proxy_send_timeout 90; proxy_read_timeout 90; client_max_body_size 10m; client_body_buffer_size 128k; proxy_buffer_size 4k; proxy_buffers 4 32k; proxy_busy_buffers_size 64k; } } } Load all the sites include /etc/nginx/conf.d/*.conf; Updates as I was not clear enough :- My question is how can I handle both the domains in the config file.My nginx is a proxy server on port 80 on an EC2 instance.This also hosts my application that runs on apache on a differnet port.So any request coming for my application will come from a domain app.mysite.com and I also want to proxy the hosted templates on S3 which are inside a bucket say sites.mysite.com/coolsite.com/index.html.So if someone hits coolsite.com I want to proxy it to the folder sites.mysite.com/coolsite.com/index.html and not to app.syartee.com.Hope I am clear The other server block: # Server for S3 server { # Listen on port 80 for all IPs associated with your machine listen 80; # Catch all other server names server_name _; //I want it to handle other domains then app.mysite.com # This code gets the host without www. in front and places it inside # the $host_without_www variable # If someone requests www.coolsite.com, then $host_without_www will have the value coolsite.com set $host_without_www $host; if ($host ~* www\.(.*)) { set $host_without_www $1; } location / { # This code rewrites the original request, and adds the host without www in front # E.g. if someone requests # /directory/file.ext?param=value # from the coolsite.com site the request is rewritten to # /coolsite.com/directory/file.ext?param=value set $foo 'http://sites.mysite.com'; # echo "$foo"; rewrite ^(.*)$ $foo/$host_without_www$1 break; # The rewritten request is passed to S3 proxy_pass http://sites.mysite.com; include /etc/nginx/proxy_params; } } Also I understand I will have to make the DNS changes in the cname of the domain.I guess I will have to add app.mysite.com under the CNAME of the template domain name?Please correct if wrong. Thank you for your time

    Read the article

  • "The server closed the connection without sending any data"

    - by Toby
    Server setup The problem Diagnostic information What I've tried Specific Help needed 1. I have the following server setup: Debian Squeeze Linux 2.6.32-5-amd64 Apache2-mpm-prefork 2.2.16-6+squeeze10 PHP 5.3.3-7+squeeze14 This server is protected with the Suhosin Patch 0.9.9.1 Max Requests Per Child: 0 - Keep Alive: on - Max Per Connection: 100 Timeouts Connection: 300 - Keep-Alive: 15 Loaded Modules core mod_log_config mod_logio prefork http_core mod_so mod_alias mod_auth_basic mod_auth_digest mod_authn_file mod_authz_default mod_authz_groupfile mod_authz_host mod_authz_user mod_cgi mod_deflate mod_dir mod_env mod_mime mod_negotiation mod_php5 mod_reqtimeout mod_rewrite mod_setenvif mod_ssl mod_status Wordpress 3.4.2 (Upgrading to 3.5 soon :) 2. The problem When I restart the server (sudo shutdown -r now), going to any website page results in the following error from the web browser (in this case, Google Chrome, but other browsers also show the same error). This error can also occur an hour or so after all is working ok, seemingly randomly, which is my biggest concern as it means my server is not reliable: No data received Unable to load the web page because the server sent no data. Here are some suggestions: Reload this web page later. Error 324 (net::ERR_EMPTY_RESPONSE): The server closed the connection without sending any data. 3. Diagnostic information The apache error log contains the folowing entries: [Fri Dec 14 22:23:27 2012] [notice] child pid 1955 exit signal Floating point exception (8) [Fri Dec 14 22:23:27 2012] [notice] child pid 1956 exit signal Floating point exception (8) [Fri Dec 14 22:23:29 2012] [notice] child pid 1957 exit signal Floating point exception (8) [Fri Dec 14 22:23:30 2012] [notice] child pid 1958 exit signal Floating point exception (8) [Fri Dec 14 22:23:32 2012] [notice] child pid 1959 exit signal Floating point exception (8) [Fri Dec 14 22:23:32 2012] [notice] child pid 1960 exit signal Floating point exception (8) [Fri Dec 14 22:23:34 2012] [notice] child pid 1961 exit signal Floating point exception (8) [Fri Dec 14 22:23:34 2012] [notice] child pid 1962 exit signal Floating point exception (8) 4. What I've tried a) I can 'fix' the website temporarily by resetting the server twice (resetting it once does not work) using the following commands. NB: the 'reload' option does not work, I have to use restart twice. However, the error can reoccur sometime later. sudo /etc/init.d/apache2 restart sudo /etc/init.d/apache2 restart b) I have tried disabling suhosin by uninstalling php5-suhosin, but a php info page still shows "This server is protected with the Suhosin Patch 0.9.9.1". I have tried putting Suhosin into simulation mode by creating a file /etc/php5/apache2/conf.d/suhosin.ini containing: [suhosin] suhosin.simulation = On The php info page shows the suhosin.ini file in the list of "Additional .ini files parsed" but the php info page still shows "This server is protected with the Suhosin Patch 0.9.9.1" c) Increasing the PHP memory limit In /etc/php5/apache2/ : ; Maximum amount of memory a script may consume (128MB) ; http://php.net/memory-limit memory_limit = 512M d) Disabling all Wordpress plugins, and going back to the default theme. 5. Specific help needed I would very much like help in debugging what is going on here. I am not sure how to determine what processes are in the Apache error log which are exiting "[notice] child pid 1955 exit signal Floating point exception (8)", or what is causing them to exit. And whether suhosin is part of the problem (and how to disable it if it is). Thank you in advance for any advice or tips you can offer in helping me debug this.

    Read the article

  • Install Ubuntu Netbook Edition with Wubi Installer

    - by Matthew Guay
    Ubuntu is one of the most popular versions of Linux, and their Netbook Remix edition is especially attractive for netbook owners.  Here we’ll look at how you can easily try out Ubuntu on your netbook without a CD/DVD drive. Netbooks, along with the growing number of thin, full powered laptops, lack a CD/DVD drive.  Installing software isn’t much of a problem since most programs, whether free or for-pay, are available for download.  Operating systems, however, are usually installed from a disk.  You can easily install Windows 7 from a flash drive with our tutorial, but installing Ubuntu from a USB flash drive is more complicated.  However, using Wubi, a Windows installer for Ubuntu, you can easily install it directly on your netbook and even uninstall it with only a few clicks. Getting Started Download and run the Wubi installer for Ubuntu (link below).  In the installer, select the drive you where you wish to install Ubuntu, the size of the installation (this is the amount dedicated to Ubuntu; under 20Gb should be fine), language, username, and desired password.  Also, from the Desktop environment menu, select Ubuntu Netbook to install the netbook edition.  Click Install when your settings are correct. Wubi will automatically download the selected version of Ubuntu and install it on your computer. Windows Firewall may ask if you want to unblock Wubi; select your network and click Allow access. The download will take around an hour on broadband, depending on your internet connection speed.  Once the download is completed, it will automatically install to your computer.  If you’d prefer to have everything downloaded before you start the install, download the ISO of Ubuntu Netbook edition (link below) and save it in the same folder as Wubi. Then, when you run Wubi, select the netbook edition as before and click Install.  Wubi will verify that your download is valid, and will then proceed to install from the downloaded ISO.  This install will only take about 10 minutes. Once the install is finished you will be asked to reboot your computer.  Save anything else you’re working on, and then reboot to finish setting up Ubuntu on your netbook. When your computer reboots, select Ubuntu at the boot screen.  Wubi leaves the default OS as Windows 7, so if you don’t select anything it will boot into Windows 7 after a few seconds. Ubuntu will automatically finish the install when you boot into it the first time.  This took about 12 minutes in our test. When the setup is finished, your netbook will reboot one more time.  Remember again to select Ubuntu at the boot screen.  You’ll then see a second boot screen; press your Enter key to select the default.   Ubuntu only took less than a minute to boot in our test.  When you see the login screen, select your name and enter your password you setup in Wubi.  Now you’re ready to start exploring Ubuntu Netbook Remix. Using Ubuntu Netbook Remix Ubuntu Netbook Remix offers a simple, full-screen interface to take the best advantage of netbooks’ small screens.  Pre-installed applications are displayed in the application launcher, and are organized by category.  Click once to open an application. The first screen on the application launcher shows your favorite programs.  If you’d like to add another application to the favorites pane, click the plus sign beside its icon. Your files from Windows are still accessible from Ubuntu Netbook Remix.  From the home screen, select Files & Folders on the left menu, and then click the icon that says something like 100GB Filesystem under the Volumes section. Now you’ll be able to see all of your files from Windows.  Your user files such as documents, music, and pictures should be located in Documents and Settings in a folder with your user name. You can also easily install a variety of free applications via the Software Installer. Connecting to the internet is also easy, as Ubuntu Netbook Remix automatically recognized the WiFi adaptor on our test netbook, a Samsung N150.  To connect to a wireless network, click the wireless icon on the top right of the screen and select the network’s name from the list. And, if you’d like to customize your screen, right-click on the application launcher and select Change desktop background. Choose a background picture you’d like. Now you’ll see it through your application launcher.  Nice! Most applications are opened full-screen.  You can close them by clicking the x on the right of the program’s name. You can also switch to other applications from their icons on the top left.  Open the home screen by clicking the Ubuntu logo in the far left. Changing Boot Options By default, Wubi will leave Windows as the default operating system, and will give you 10 seconds at boot to choose to boot into Ubuntu.  To change this, boot into Windows and enter Advanced system settings in your start menu search. In this dialog, click Settings under Startup and Recovery. From this dialog, you can select the default operating system and the time to display list of operating systems.  You can enter a lower number to make the boot screen appear for less time. And if you’d rather make Ubuntu the default operating system, select it from the drop-down list.   Uninstalling Ubuntu Netbook Remix If you decide you don’t want to keep Ubuntu Netbook Remix on your computer, you can uninstall it just like you uninstall any normal application.  Boot your computer into Windows, open Control Panel, click Uninstall a Program, and enter ubuntu in the search box.  Select it, and click Uninstall. Click Uninstall at the prompt.  Ubuntu uninstalls very quickly, and removes the entry from the bootloader as well, so your computer is just like it was before you installed it.   Conclusion Ubuntu Netbook Remix offers an attractive Linux interface for netbooks.  We enjoyed trying it out, and found it much more user-friendly than most Linux distros.  And with the Wubi installer, you can install it risk-free and try it out on your netbook.  Or, if you’d like to try out another alternate netbook operating system, check out our article on Jolicloud, another new OS for netbooks. Links Download Wubi Installer for Windows Download Ubuntu Netbook Edition Similar Articles Productive Geek Tips Easily Install Ubuntu Linux with Windows Using the Wubi InstallerInstall VMware Tools on Ubuntu Edgy EftHow to install Spotify in Ubuntu 9.10 using WineInstalling PHP5 and Apache on UbuntuInstalling PHP4 and Apache on Ubuntu TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips VMware Workstation 7 Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Explorer++ is a Worthy Windows Explorer Alternative Error Goblin Explains Windows Error Codes Twelve must-have Google Chrome plugins Cool Looking Skins for Windows Media Player 12 Move the Mouse Pointer With Your Face Movement Using eViacam Boot Windows Faster With Boot Performance Diagnostics

    Read the article

  • Twitter traffic might not be what it seems

    - by Piet
    Are you using bit.ly stats to measure interest in the links you post on twitter? I’ve been hearing for a while about people claiming to get the majority of their traffic originating from twitter these days. Now, I’ve been playing with the twitter ruby gem recently, doing various experiments which I’ll not go into detail here because they could be regarded as spamming… if I’d conduct them on a large scale, that is. It’s scary to see people actually engaging with @replies crafted with some regular expressions and eliza-like trickery on status updates found using the twitter api. I’m wondering how Twitter is going to contain the coming spam-flood. When posting links I used bit.ly as url shortener, since this one seems to be the de-facto standard on twitter. A nice thing about bit.ly is that it shows some basic stats about the redirects it performs for your shortened links. To my surprise, most links posted almost immediately resulted in several visitors. Now, seeing that I was posting the links together with some information concerning what the link is about, I concluded that the people who were actually clicking the links should be very targeted visitors. This felt a bit like free adwords, and I suddenly started to understand why everyone was raving about getting traffic from twitter. How wrong I was! (and I think several 1000 online marketers with me) On the destination site I used a traffic logging solution that works by including a little javascript snippet in your pages. It seemed that somehow all visitors disappeared after the bit.ly redirect and before getting to the site, because I was hardly seeing any visitors there. So I started investigating what was happening: by looking at the logfiles of the destination site, and by making my own ’shortened’ urls by doing redirects using a very short domain name I own. This way, I could check the apache access_log before the redirects. Most user agents turned out to be bots without a doubt. Here’s an excerpt of user-agents awk’ed from apache’s access_log for a time period of about one hour, right after posting some links: AideRSS 2.0 (postrank.com) Java/1.6.0_13 Java/1.6.0_14 libwww-perl/5.816 MLBot (www.metadatalabs.com/mlbot) Mozilla/4.0 (compatible;MSIE 5.01; Windows -NT 5.0 - real-url.org) Mozilla/5.0 (compatible; Twitturls; +http://twitturls.com) Mozilla/5.0 (compatible; Viralheat Bot/1.0; +http://www.viralheat.com/) Mozilla/5.0 (Danger hiptop 4.6; U; rv:1.7.12) Gecko/20050920 Mozilla/5.0 (X11; U; Linux i686; en-us; rv:1.9.0.2) Gecko/2008092313 Ubuntu/9.04 (jaunty) Firefox/3.5 OpenCalaisSemanticProxy PycURL/7.18.2 PycURL/7.19.3 Python-urllib/1.17 Twingly Recon twitmatic Twitturly / v0.6 Wget/1.10.2 (Red Hat modified) Wget/1.11.1 (Red Hat modified) Of the few user-agents that seem ‘real’ at first, half are originating from an ip-address used by Amazon EC2. And I doubt people are setting op proxies on there. Oh yeah, Googlebot (the real deal, from a legit google owned address) is sucking up posted links like fresh oysters. I guess google is trying to make sure in advance to never be beaten by twitter in the ‘realtime search’ department. Actually, I think it’d be almost stupid NOT to post any new pages/posts/websites on Twitter, it must be one of the fastest ways to get a Googlebot visit. Same experiment with a real, established twitter account Now, because I was posting the url’s either as ’status’ messages or directed @people, on a test-account with hardly any (human) followers, I checked again using the twitter accounts from a commercial site I’m involved with. These accounts all have between 500 and 1000 targeted (I think) followers. I checked the destination access_logs and also added ‘my’ redirect after the bit.ly redirect: same results, although seemingly a bit higher real visitor/bot ratio. Btw: one of these account was ‘punished’ with a 1 week lock recently because the same (1 one!) status update was sent that was sent right before using another account. They got an email explaining the lock because the account didn’t act according to their TOS. I can’t find anything in their TOS about it, can you? I don’t think Twitter is on the right track punishing a legit account, knowing the trickery I had been doing with it’s api went totally unpunished. I might be wrong though, I often am. On the other hand: this commercial site reported targeted traffic and actual signups from visitors coming from Twitter. The ones that are really real visitors are also very targeted. I’m just not sure if the amount of work involved could hold up against an adwords campaign. Reposting the same link over and over again helps On thing I noticed: It helps to keep on reposting the same links with regular intervals. I guess most people only look at their first page when checking out recent posts of the ones they’re following, or don’t look too far back when performing a search. Now, this probably isn’t according to the twitter TOS. Actually, it might be spamming but no-one is obligated to follow anyone else of course. This way, I was getting more real visitors and less bots. To my surprise (when my programmer’s hat is on) there were still repeated visits from the same bots coming from the same ip-addresses. Did they expect to find something else when visiting for a 2nd or 3rd time? (actually,this gave me an idea: you can’t change a link once it’s posted, but you can change where it redirects to) Most bots were smart enough not to follow the same link again though. Are you successful in getting real visitors from Twitter? Are you only relying on bit.ly to provide traffic stats?

    Read the article

  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

    Read the article

  • Turn A Flash Drive Into a Portable Web Server

    - by Matthew Guay
    Portable applications are very useful for getting work done on the go, but how about portable servers?  Here’s how you can turn your flash drive into a portable web server. Getting Started To put a full web server on our flash drive, we’re going to use XAMPP Lite.  This lightweight, preconfigured server includes recent versions of Apache, MySQL, and PHP so you can run most websites and webapps directly from it.  You could use the full XAMPP, which includes more features such as a FileZilla FTP server and OpenSSL, but for most purposes, the light version is plenty for a portable server. Download the latest version of XAMPP Lite (link below).  In this tutorial, we used the self-extracting EXE version; you could choose the ZIP file and extract the files yourself, but we found it easier to use the executable. Run the installer, and click Browse choose where to install your server. Select your flash drive, or a folder in it, and click Ok.  Make sure your flash drive has at least 250MB of available storage space.  XAMPP will create an xampplite folder and store all the files in it during the installation.   Click Install, and all of the files will be extracted to your flash drive.  This may take a few moments depending on your flash drive’s speed. When the extraction process is finished, a Command Prompt window will open to finish the installation.  The first prompt will ask if you want to add shortcuts to the start menu and desktop; enter “n” since we don’t want to create start menu links to our portable server. Now enter “y” to configure XAMPP’s directories automatically. Finally, enter “y” to make XAMPP fully portable.  It will set up the servers to run without specific drive letters so your server will run from any computer. XAMPP will finalize your changes; press Enter when everything is completed. Setup will automatically launch the command line version of XAMPP.  On first run, confirm that your time zone is correct. And that’s it!  You can now run XAMPP’s control panel by entering 1, or you can exit and run XAMPP from any other computer with your flash drive. To complete your portable webserver kit, you may want to install Portable Firefox or Iron Browser on your flash drive so you always have your favorite browser ready to use. Running your portable server Using your portable server is very simple.  Open the xampplite folder on your flash drive and launch xampp-control.exe. Click Start beside Apache and MySql to get your webserver running. Please note: Do not check the Svc box, as this will run the server as a Windows service.  To keep XAMPP portable, you do not want it running as a service! Windows Firewall may prompt you that it blocked the server; click Allow access to let your server run. Once they’re running, you can click Admin to open the default XAMPP admin page running from your local webserver.  Or, you can view it by browsing to http://localhost/ or http://127.0.0.1/ in your browser. If everything is working correctly, you should see this page in your browser.  Choose your default language… And then you’ll see the default XAMPP admin page.   Click the Status link on the left sidebar to make sure everything is running correctly. If you click the Admin button for MySql in the XAMPP Control Panel, it will open phpMyAdmin in your default browser.  Alternately, you can open the MySql admin page by entering http://localhost/phpmyadmin/ or http://127.0.0.1/phpmyadmin/ in your favorite browser. Now you can add your own webpages to your webserver.  Save all of your web files in the \xampplight\htdocs\ folder on your flash drive. Install WordPress in your portable server Since XAMPP Lite includes MySql and PHP, you can even run webapps such as WordPress, the popular CMS and blogging platform.  Download WordPress (link below), and extract the files to the \xampplite\htdocs folder on your flash drive. Now all of the WordPress files are stored in \xampplite\htdocs\wordpress on your flash drive. We still need to setup WordPress on our portable server.  Open your MySql admin page http://localhost/phpmyadmin/ to create a new database for WordPress.  Enter a name for your database in the “Create new database” box, and click Create. Click the Privileges tab on the top, and the select “Add a new User”.   Enter a username and password for the database, and then click the Go button on the bottom of the page. Using WordPress Now, in your browser, enter http://localhost/wordpress/wp-admin/install.php.  Click Create a Configuration File to continue. Make sure you have your Database name, username, and password we created previously, and click “Let’s Go!” Enter your WordPress database name, username, and password, leave the other two entries as default, and click Submit. You should now have the database all ready to go.  Click “Run the install” to finish installing WordPress. Enter a title, username, and password for your test blog, as well as your email address, and then click “Install WordPress”. You now have a portable install of WordPress.  Click “Log In” to  access your WordPress admin page. Enter your username and password, and click Log In. Here you can add pages, posts, themes, extensions, and anything else just like you would on a normal WordPress site.  This is a great way to experiment with WordPress without messing up your real website. You can view your portable WordPress site by entering http://localhost/wordpress/ in your address bar. Closing your server When you’re done running your test server, click the Stop button on each of the services and then click the Exit button in the XAMPP control panel.  If you press the exit button on the top of the window, it will just minimize the control panel to the tray.   Alternately, you can shutdown your server by running xampp_stop.exe from your xampplite folder. Conclusion XAMPP Lite gives you a great way to run a full webserver directly from your flash drive.  Now, anywhere you go, you can test and tweak your webpages and webapps from any Windows computer.  Links Download XAMPP Lite Download WordPress Similar Articles Productive Geek Tips BitLocker To Go Encrypts Portable Flash Drives in Windows 7How To Use BitLocker on Drives without TPMSpeed up Your Windows Vista Computer with ReadyBoostView and Manage Flash Cookies the Easy WayInstall and Run Applications from Your iPod, Flash Drive or Mp3 Player TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 OutlookStatView Scans and Displays General Usage Statistics How to Add Exceptions to the Windows Firewall Office 2010 reviewed in depth by Ed Bott FoxClocks adds World Times in your Statusbar (Firefox) Have Fun Editing Photo Editing with Citrify Outlook Connector Upgrade Error

    Read the article

  • How to upgrade boost lib using apt-get?

    - by sam
    I use ubuntu 11.04. My boost version: sam@sam:~/code/ros/pcl$ apt-cache showpkg libboost-all-dev Package: libboost-all-dev Versions: 1.42.0.1ubuntu1 (/var/lib/apt/lists/tw.archive.ubuntu.com_ubuntu_dists_natty_universe_binary-amd64_Packages) (/var/lib/dpkg/status) Description Language: File: /var/lib/apt/lists/tw.archive.ubuntu.com_ubuntu_dists_natty_universe_binary-amd64_Packages MD5: 72efad05a3c79394c125b79e1d4eb3a7 Reverse Depends: libvtk5-dev,libboost-all-dev libfeel++-dev,libboost-all-dev Dependencies: 1.42.0.1ubuntu1 - libboost-dev (0 (null)) libboost-date-time-dev (0 (null)) libboost-filesystem-dev (0 (null)) libboost-graph-dev (0 (null)) libboost-iostreams-dev (0 (null)) libboost-math-dev (0 (null)) libboost-program-options-dev (0 (null)) libboost-python-dev (0 (null)) libboost-regex-dev (0 (null)) libboost-serialization-dev (0 (null)) libboost-signals-dev (0 (null)) libboost-system-dev (0 (null)) libboost-test-dev (0 (null)) libboost-thread-dev (0 (null)) libboost-wave-dev (0 (null)) Provides: 1.42.0.1ubuntu1 - Reverse Provides: sam@sam:~/code/ros/pcl$ How to upgrade boost to 1.44+ by using apt tools? Thank you~ When I run apt-add-repository,it shows: sam@sam:~/code/ros/pcl$ sudo apt-add-repository ppa:timklingt/ppa Error reading https://launchpad.net/api/1.0/~timklingt/+archive/ppa: GnuTLS recv error (-9): A TLS packet with unexpected length was received. sam@sam:~/code/ros/pcl$ How to fix it? Thank you~ I try to install libboost1.46-all-dev: sam@sam:~/code/ros/pcl$ sudo apt-get install libboost1.46-all-dev Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: libboost1.46-all-dev : Depends: libboost1.46-dev but it is not going to be installed Depends: libboost-date-time1.46-dev but it is not going to be installed Depends: libboost-filesystem1.46-dev but it is not going to be installed Depends: libboost-graph1.46-dev but it is not going to be installed Depends: libboost-iostreams1.46-dev but it is not going to be installed Depends: libboost-math1.46-dev but it is not going to be installed Depends: libboost-program-options1.46-dev but it is not going to be installed Depends: libboost-python1.46-dev but it is not going to be installed Depends: libboost-regex1.46-dev but it is not going to be installed Depends: libboost-serialization1.46-dev but it is not going to be installed Depends: libboost-signals1.46-dev but it is not going to be installed Depends: libboost-system1.46-dev but it is not going to be installed Depends: libboost-test1.46-dev but it is not going to be installed Depends: libboost-thread1.46-dev but it is not going to be installed Depends: libboost-wave1.46-dev but it is not going to be installed E: Broken packages sam@sam:~/code/ros/pcl$ What's these error means? And how to solve it? Thank you~

    Read the article

  • box2D simulation doesn't work

    - by shadow_of__soul
    has been a while since last time i used box2D, and i needed to make some stuff, and i saw that my simulation don't worked (compiles, but do anything). i haven't been able to even have working the examples or this simple example i'm pasting below: package { import flash.display.Sprite; import flash.events.Event; import Box2D.Common.Math.b2Vec2; import Box2D.Dynamics.b2World; import Box2D.Dynamics.b2BodyDef; import Box2D.Dynamics.b2Body; import Box2D.Collision.Shapes.b2CircleShape; import Box2D.Dynamics.b2Fixture; import Box2D.Dynamics.b2FixtureDef; import org.flashdevelop.utils.FlashConnect; import flash.events.TimerEvent; import flash.utils.Timer; public class Main extends Sprite { public var world:b2World; public var wheelBody:b2Body; public var stepTimer:Timer; public function Main():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); var gravity:b2Vec2 = new b2Vec2(0, 10); world = new b2World(gravity, true); var wheelBodyDef:b2BodyDef = new b2BodyDef(); wheelBodyDef.type = b2Body.b2_dynamicBody; wheelBody = world.CreateBody(wheelBodyDef); var circleShape:b2CircleShape = new b2CircleShape(5); var wheelFixtureDef:b2FixtureDef = new b2FixtureDef(); wheelFixtureDef.shape = circleShape; var wheelFixture:b2Fixture = wheelBody.CreateFixture(wheelFixtureDef); stepTimer = new Timer(0.025 * 1000); stepTimer.addEventListener(TimerEvent.TIMER, onTick); FlashConnect.trace(wheelBody.GetPosition().x, wheelBody.GetPosition().y); stepTimer.start(); // entry point } private function onTick(a_event:TimerEvent):void { world.Step(0.025, 10, 10); FlashConnect.trace(wheelBody.GetPosition().x, wheelBody.GetPosition().y); } } } on this, the object should fall down, but the positions reported me by the trace method, are always 0. so is not a display problem, that i see everything freeze, is why the simulation is not working, and i have no idea why :( can anyone point me to the right direction of where i need to look for the problem? my settings are: windows 7 flashdevelop 4.2.1 SDK: 4.6.0 compiling for flash 10, but i tried every target i have available (till flash 11.5) project set at 30fps

    Read the article

  • Gawker Passwords

    - by Nick Harrison
    There has been much news about the hack of the Gawker web sites. There has even been an analysis of the common passwords found. This list is embarrassing in many ways. The most common password was "123456". The second most common password was "password". Much has also been written providing advice on how to create good passwords. This article provides some interesting advice, none of which should be taken. Anyone reading my blog, probably already knows the importance of strong passwords, so I am not going to reiterate the reasons here. My target audience is more the folks defining password complexity requirements. A user cannot come up with a strong password, if we have complexity requirements that don't make sense. With that in mind, here are a few guidelines:  Long Passwords Insist on long passwords. In some cases, you may need to change to allow a long password. I have seen many places that cap passwords at 8 characters. Passwords need to be at least 8 characters minimal. Consider how much stronger the passwords would be if you double the length. Passwords that are 15-20 characters will be that much harder to crack. There is no need to have limit passwords to 8 characters. Don't Require Special Characters Many complexity rules will require that your password include a capital letter, a lower case letter, a number, and one of the "special" characters, the shits above the number keys. The problem with such rules is that the resulting passwords are harder to remember. It also means that you will have a smaller set of characters in the resulting passwords. If you must include one of the 9 digits and one of the 9 "special" characters, then you have dramatically reduced the character set that will make up the final password. Two characters will be one of 10 possible values instead of one of 70. Two additional characters will be one of 26 possible characters instead of a 70 character potential character set. If you limit passwords to 8 characters, you are left with only 7 characters having the full set of 70 potential values. With these character restrictions in place, there are 1.6 x1012 possible passwords. Without these special character restrictions, but allowing numbers and special characters, you get a total of 5.76x1014 possible passwords. Even if you only allowed upper and lower case characters, you will still have 2.18X1014 passwords. You can do the math any number of ways, requiring special characters will always weaken passwords. Now imagine the number of passwords when you require more than 8 characters.  If you are responsible for defining complexity rules, I urge you to take these guidelines into account. What other guidelines do you follow?

    Read the article

  • Camera rotation - First Person Camera using GLM

    - by tempvar
    I've just switched from deprecated opengl functions to using shaders and GLM math library and i'm having a few problems setting up my camera rotations (first person camera). I'll show what i've got setup so far. I'm setting up my ViewMatrix using the glm::lookAt function which takes an eye position, target and up vector // arbitrary pos and target values pos = glm::vec3(0.0f, 0.0f, 10.0f); target = glm::vec3(0.0f, 0.0f, 0.0f); up = glm::vec3(0.0f, 1.0f, 0.0f); m_view = glm::lookAt(pos, target, up); i'm using glm::perspective for my projection and the model matrix is just identity m_projection = glm::perspective(m_fov, m_aspectRatio, m_near, m_far); model = glm::mat4(1.0); I send the MVP matrix to my shader to multiply the vertex position glm::mat4 MVP = camera->getProjection() * camera->getView() * model; // in shader gl_Position = MVP * vec4(vertexPos, 1.0); My camera class has standard rotate and translate functions which call glm::rotate and glm::translate respectively void camera::rotate(float amount, glm::vec3 axis) { m_view = glm::rotate(m_view, amount, axis); } void camera::translate(glm::vec3 dir) { m_view = glm::translate(m_view, dir); } and i usually just use the mouse delta position as the amount for rotation Now normally in my previous opengl applications i'd just setup the yaw and pitch angles and have a sin and cos to change the direction vector using (gluLookAt) but i'd like to be able to do this using GLM and matrices. So at the moment i have my camera set 10 units away from the origin facing that direction. I can see my geometry fine, it renders perfectly. When i use my rotation function... camera->rotate(mouseDeltaX, glm::vec3(0, 1, 0)); What i want is for me to look to the right and left (like i would with manipulating the lookAt vector with gluLookAt) but what's happening is It just rotates the model i'm looking at around the origin, like im just doing a full circle around it. Because i've translated my view matrix, shouldn't i need to translate it to the centre, do the rotation then translate back away for it to be rotating around the origin? Also, i've tried using the rotate function around the x axis to get pitch working, but as soon as i rotate the model about 90 degrees, it starts to roll instead of pitch (gimbal lock?). Thanks for your help guys, and if i've not explained it well, basically i'm trying to get a first person camera working with matrix multiplication and rotating my view matrix is just rotating the model around the origin.

    Read the article

  • Silverlight Cream for June 10, 2010 -- #879

    - by Dave Campbell
    In this Issue: Emiel Jongerius, Nokola, Christian Schormann, Tim Heuer, David Poll, Mike Snow(-2-), John Papa, and Charles Petzold. Shoutout: Viktor Larsson has a frank look at WP7 based on information from MIX10 and what was said this week in his post: Licking Windows Phone 7... yeah licking, not liking :) .. my guess is even that didn't allow him to keep it! If you haven't already noticed, the CodeProject reader's choice awards are out this week and Telerik won for their RadColorPicker and RadCalendar for Silverlight Telerik also needs congratulations for winning Telerik wins “Best of TechEd” award in the “Components and Middleware” category... check out that trophy... Steven Forte has a picture up of the Telerikers after getting the award. Koen Zwikstra has a new release of Silverlight Spy up that supports the latest release: Silverlight Spy 3.0.0.12 From SilverlightCream.com: Localization of XAML files in Silverlight Emiel Jongerius is back with another post, this time discussing Localizing XAM files... external links and source included. Coolest Silverlight Sound Library for Games I've Seen Yet Nokola talks up a Sound Library for Silverlight 4 Games ... and has links to a great demo, plus the source. SketchFlow: Firing Actions when a Storyboard is Complete Christian Schormann responded to some Twitter questions and demonstrates using the StoryboardCompleted trigger with a Navigate action. Hosting cross-domain Silverlight applications (XAP) Tim Heuer responds to a question from a reader and demonstrates how to host a XAP from a domain other than the one you're working on. Taking Microsoft Silverlight 4 Applications Beyond the Browser (TechEd WEB313) David Poll has all his material up from his TechEd presentation earlier this week on Silverlight OOB... and he covered some pretty extensive material ... check it out! Silverlight Tip of the Day #29 – Configuring Service Reference to Back to LocalHost Mike Snow has a couple new tips up... this first one is quick, but very useful... how to switch your service reference back to localhost without pulling out your hair. Silverlight Tip of the Day #30 – Sending Email from Silverlight In Mike Snow's latest tip, he shows how to send email from your Silverlight app... using a WCF service... and a step-by-step set of instructions. Creating Rich Interactions Using Blend 4: Transition Effects, Fluid Layout and Layout States (Silverlight TV #32) John Papa has Silverlight TV #32 up, and he's talking with Kenny Young of the Expression Blend team while Kenny uses some built-om effects and also creates some impressive examples from scratch -- code included. Simulating Touch Inertia on Windows Phone 7 Charles Petzold has a post up on simulating inertia on WP7... demos in WPF and then moves into WP7... math, source, and external links. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

    Read the article

  • How can I get my progress reviewed as a solo junior developer

    - by Oliver Hyde
    I am currently working for a 2 person company, as the solo primary developer. My boss gets the clients, mocks up some png design templates and hands them over to me. This system has been working fine and i'm really enjoying it. The types of projects I work on are for small - medium sized businesses and they usually want a CMS system. Developed from scratch i'll build a customised backend for the client to add/edit/remove categories, tags, products etc and then output them to the front end according to the design template handed to me. As time has gone on, the projects have increased in complexity, with shopping cart / ordering features and other common e-commerce type features. Again, this system has been working fine and i'm really enjoying it. My issue is my personal development as a programmer. I spend a lot of my spare time reading programming blogs, checking through stackexchange, reading suggested programming books (currently on 'The Pragmatic Programmer', really good so far), doing brain exercises (lumosity.com and khanacademy math problems), doing lots of physical exercise and other personal development type activities. I can't help but feel though, that I'm missing out on feedback, critique. My boss is great and never holds back on praise in regards to my work, but he unfortunately is either to busy to check my code, or to be honest, I don't think it's one of his specialties and so can't provide feedback. I want to know what i'm doing wrong and what i'm doing right. Should I be putting that much logic in the controller, am I modulating my code enough etc. So what I have done is developed a little 'Family Budgeting' app and tried to do it as cleanly and effectively as I currently know how. What i'm wanting to know is, is there somewhere I can submit this app, and have some seasoned developers provide feedback. It's not just a subsection of my code like 'codereview.stackexchange' appears to require, it's my entire workflow that I want critiqued. I know this is a lot to ask, and I expect the main advice given will be to look for a job within a team, which is certainly something I will look into later down the track, but for now I want to persist with my current employment situation, but just don't want to develop too many bad habits. Let me know if I can provide any further information to help clarify, or if this isn't the right place for this type of question I apologise in advance. Didn't want to use reddit as I felt this community fosters more well thought out responses.

    Read the article

  • C# XNA Normals Question

    - by Wade
    Hello all! I have been working on some simple XNA proof of concept for a game idea I have as well as just to further my learning in XNA. However, i seem to be stuck on these dreaded normals, and using the BasicEffect with default lighting i can't seem to tell if my normals are being calculated correctly, hence the question. I'm mainly drawing cubes at the moment, I'm using a triangle list and a VertexBuffer to get the job done. The north face of my cube has two polygons and 6 vectors: Vector3 startPosition = new Vector3(0,0,0); corners[0] = startPosition; // This is the start position. Block size is 5. corners[1] = new Vector3(startPosition.X, startPosition.Y + BLOCK_SIZE, startPosition.Z); corners[2] = new Vector3(startPosition.X + BLOCK_SIZE, startPosition.Y, startPosition.Z); corners[3] = new Vector3(startPosition.X + BLOCK_SIZE, startPosition.Y + BLOCK_SIZE, startPosition.Z); verts[0] = new VertexPositionNormalTexture(corners[0], normals[0], textCoordBR); verts[1] = new VertexPositionNormalTexture(corners[1], normals[0], textCoordTR); verts[2] = new VertexPositionNormalTexture(corners[2], normals[0], textCoordBL); verts[3] = new VertexPositionNormalTexture(corners[3], normals[0], textCoordTL); verts[4] = new VertexPositionNormalTexture(corners[2], normals[0], textCoordBL); verts[5] = new VertexPositionNormalTexture(corners[1], normals[0], textCoordTR); Using those coordinates I want to generate the normal for the north face, I have no clue how to get the average of all those vectors and create a normal for the two polygons that it makes. Here is what i tried: normals[0] = Vector3.Cross(corners[1], corners[2]); normals[0].Normalize(); It seems like its correct, but then using the same thing for other sides of the cube the lighting effect seems weird, and not cohesive with where i think the light source is coming from, not really sure with the BasicEffect. Am I doing this right? Can anyone explain in lay mans terms how normals are calculated. Any help is much appreciated. Note: I tried going through Riemers and such to figure it out with no luck, it seems no one really goes over the math well enough. Thanks!

    Read the article

  • Is it wise to store a big lump of json on a database row

    - by Ieyasu Sawada
    I have this project which stores product details from amazon into the database. Just to give you an idea on how big it is: [{"title":"Genetic Engineering (Opposing Viewpoints)","short_title":"Genetic Engineering ...","brand":"","condition":"","sales_rank":"7171426","binding":"Book","item_detail_url":"http://localhost/wordpress/product/?asin=0737705124","node_list":"Books > Science & Math > Biological Sciences > Biotechnology","node_category":"Books","subcat":"","model_number":"","item_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=128","details_url":"http://localhost/wordpress/product/?asin=0737705124","large_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/large-notfound.png","medium_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/medium-notfound.png","small_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/small-notfound.png","thumbnail_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/thumbnail-notfound.png","tiny_img":"http://localhost/wordpress/wp-content/plugins/ecom/img/tiny-notfound.png","swatch_img":"http://localhost/wordpress/wp-content/plugins/ecom/img/swatch-notfound.png","total_images":"6","amount":"33.70","currency":"$","long_currency":"USD","price":"$33.70","price_type":"List Price","show_price_type":"0","stars_url":"","product_review":"","rating":"","yellow_star_class":"","white_star_class":"","rating_text":" of 5","reviews_url":"","review_label":"","reviews_label":"Read all ","review_count":"","create_review_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=132","create_review_label":"Write a review","buy_url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=19186","add_to_cart_action":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/add_to_cart.php","asin":"0737705124","status":"Only 7 left in stock.","snippet_condition":"in_stock","status_class":"ninstck","customer_images":["http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/31FIM-YIUrL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg","http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/51M2vvFvs2BL.jpg"],"disclaimer":"","item_attributes":[{"attr":"Author","value":"Greenhaven Press"},{"attr":"Binding","value":"Hardcover"},{"attr":"EAN","value":"9780737705126"},{"attr":"Edition","value":"1"},{"attr":"ISBN","value":"0737705124"},{"attr":"Label","value":"Greenhaven Press"},{"attr":"Manufacturer","value":"Greenhaven Press"},{"attr":"NumberOfItems","value":"1"},{"attr":"NumberOfPages","value":"224"},{"attr":"ProductGroup","value":"Book"},{"attr":"ProductTypeName","value":"ABIS_BOOK"},{"attr":"PublicationDate","value":"2000-06"},{"attr":"Publisher","value":"Greenhaven Press"},{"attr":"SKU","value":"G0737705124I2N00"},{"attr":"Studio","value":"Greenhaven Press"},{"attr":"Title","value":"Genetic Engineering (Opposing Viewpoints)"}],"customer_review_url":"http://localhost/wordpress/wp-content/ecom-customer-reviews/0737705124.html","flickr_results":["http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/5105560852_06c7d06f14_m.jpg"],"freebase_text":"No around the web data available yet","freebase_image":"http://localhost/wordpress/wp-content/plugins/ecom/img/freebase-notfound.jpg","ebay_related_items":[{"title":"Genetic Engineering (Introducing Issues With Opposing Viewpoints), , Good Book","image":"http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/140.jpg","url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=12165","currency_id":"$","current_price":"26.2"},{"title":"Genetic Engineering Opposing Viewpoints by DAVID BENDER - 1964 Hardcover","image":"http://localhost/wordpress/wp-content/uploads/2013/10/ecom_images/140.jpg","url":"http://localhost/wordpress/wp-content/ecom-plugin-redirects/ecom_redirector.php?id=130","currency_id":"AUD","current_price":"11.99"}],"no_follow":"rel=\"nofollow\"","new_tab":"target=\"_blank\"","related_products":[],"super_saver_shipping":"","shipping_availability":"","total_offers":"7","added_to_cart":""}] So the structure for the table is: asin title details (the product details in json) Will the performance suffer if I have to store like 10,000 products? Is there any other way of doing this? I'm thinking of the following, but the current setup is really the most convenient one since I also have to use the data on the client side: store the product details in a file. So something like ASIN123.json store the product details in one big file. (I'm guessing it will be a drag to extract data from this file) store each of the fields in the details in its own table field Thanks in advance!

    Read the article

  • JavaScript in different browsers

    - by PointsToShare
    Adventures with JavaScript rendered in IE 8, Chrome 15, and Firefox 8.0 I have written a little monogram about the advantages of Math and wrote a few JavaScript applications to demonstrate them. I was a bit careless and used elements on the page in my JavaScript without using any of the GetElementsByXXXX methods to identify them.  Say I had a text box named tbSeqNum into which I entered a number to be used in a computation. In my code I simply referred to its value by using it directly. Like here: Function Blah() {                 return tbSeqNum.value; } This ran fine in IE8. In IE, the elements are available as global variables. This is not the case in either Firefox or Chrome. In there one has to create the variable and only then use it. Assuming I also used tbSeqNum as the element’s ID, this works: Function Blah() {                 return GetElementById(“tbSeqNum”).value; } Naturally this corrected function also works in IE, so be warned. Also, coming from windows programming (I am long in the tooth and programmed long before the internet), I have a habit of putting an “Exit” button on my pages and setting their onclick to: onclick=”window.close()”. Again, this works fine in IE. In Firefox and chrome, it does not! There you can only close a window that you opened in the code. A window that was opened by navigation to a URL will not close.  Before I deployed mu code to my website, I painfully removed all my Exit buttons. But my greatest surprise came when I tested my pages in the various browsers. In my code I do a comparison on the performance of two algorithms used to solve the same problem. One is brute force, the other uses a mathematical formula. The compare functions runs each many times and displays the time it took for each and also the ratio. Chrome runs JavaScript between 5 and 10 times faster than Firefox and between 50 and 100 times faster that IE. Wow!!! This difference is especially remarkable when the code uses iteration. I suspect that the JS engines in Chrome and Firefox simply cache the result of a function and if it is called again with the same parameters, it returns the cached result. To see it in action play run the “How Many Squares” page in www.mgsltns.com/games.htm The host is running on Unix, so the link is case sensitive. Last Note: IE9 runs JS a bit faster, but still lags behind almost as badly. That’s All Folks!

    Read the article

  • Microsoft and the open source community

    - by Charles Young
    For the last decade, I have repeatedly, in my imitable Microsoft fan boy style, offered an alternative view to commonly held beliefs about Microsoft's stance on open source licensing.  In earlier times, leading figures in Microsoft were very vocal in resisting the idea that commercial licensing is outmoded or morally reprehensible.  Many people interpreted this as all-out corporate opposition to open source licensing.  I never read it that way. It is true that I've met individual employees of Microsoft who are antagonistic towards FOSS (free and open source software), but I've met more who are supportive or at least neutral on the subject.  In any case, individual attitudes of employees don't necessarily reflect a corporate stance.  The strongest opposition I've encountered has actually come from outside the company.  It's not a charitable thought, but I sometimes wonder if there are people in the .NET community who are opposed to FOSS simply because they believe, erroneously, that Microsoft is opposed. Here, for what it is worth, are the points I've repeated endlessly over the years and which have often been received with quizzical scepticism. a)  A decade ago, Microsoft's big problem was not FOSS per se, or even with copyleft.  The thing which really kept them awake at night was the fear that one day, someone might find, deep in the heart of the Windows code base, some code that should not be there and which was published under GPL.  The likelihood of this ever happening has long since faded away, but there was a time when MS was running scared.  I suspect this is why they held out for a while from making Windows source code open to inspection.  Nowadays, as an MVP, I am positively encouraged to ask to see Windows source. b)  Microsoft has never opposed the open source community.  They have had problems with specific people and organisations in the FOSS community.  Back in the 1990s, Richard Stallman gave time and energy to a successful campaign to launch antitrust proceedings against Microsoft.  In more recent times, the negative attitude of certain people to Microsoft's submission of two FOSS licences to the OSI (both of which have long since been accepted), and the mad scramble to try to find any argument, however tenuous, to block their submission was not, let us say, edifying. c) Microsoft has never, to my knowledge, written off the FOSS model.  They certainly don't agree that more traditional forms of licensing are inappropriate or immoral, and they've always been prepared to say so.  One reason why it was so hard to convince people that Microsoft is not rabidly antagonistic towards FOSS licensing is that so many people think they have no involvement in open source.  A decade ago, there was virtually no evidence of any such involvement.  However, that was a long time ago.  Quietly over the years, Microsoft has got on with the job of working out how to make use of FOSS licensing and how to support the FOSS community.  For example, as well as making increasingly extensive use of Github, they run an important FOSS forge (CodePlex) on which they, themselves, host many hundreds of distinct projects.  The total count may even be in the thousands now.  I suspect there is a limit of about 500 records on CodePlex searches because, for the past few years, whenever I search for Microsoft-specific projects on CodePlex, I always get approx. 500 hits.  Admittedly, a large volume of the stuff they publish under FOSS licences amounts to code samples, but many of those 'samples' have grown into useful and fully featured frameworks, libraries and tools. All this is leading up to the observation that yesterday's announcement by Scott Guthrie marks a significant milestone and should not go unnoticed.  If you missed it, let me summarise.   From the first release of .NET, Microsoft has offered a web development framework called ASP.NET.  The core libraries are included in the .NET framework which is released free of charge, but which is not open source.   However, in recent years, the number of libraries that constitute ASP.NET have grown considerably.  Today, most professional ASP.NET web development exploits the ASP.NET MVC framework.  This, together with several other important parts of the ASP.NET technology stack, is released on CodePlex under the Apache 2.0 licence.   Hence, today, a huge swathe of web development on the .NET/Azure platform relies four-square on the use of FOSS frameworks and libraries. Yesterday, Scott Guthrie announced the next stage of ASP.NET's journey towards FOSS nirvana.  This involves extending ASP.NET's FOSS stack to include Web API and the MVC Razor view engine which is rapidly becoming the de facto 'standard' for building web pages in ASP.NET.  However, perhaps the more important announcement is that the ASP.NET team will now accept and review contributions from the community.  Scott points out that this model is already in place elsewhere in Microsoft, and specifically draws attention to development of the Windows Azure SDKs.  These SDKs are central to Azure development.   The .NET and Java SDKs are published under Apache 2.0 on Github and Microsoft is open to community contributions.  Accepting contributions is a more profound move than simply releasing code under FOSS licensing.  It means that Microsoft is wholeheartedly moving towards a full-blooded open source approach for future evolution of some of their central and most widely used .NET and Azure frameworks and libraries.  In conjunction with Scott's announcement, Microsoft has also released Git support for CodePlex (at long last!) and, perhaps more importantly, announced significant new investment in their own FOSS forge. Here at Solidsoft we have several reasons to be very interested in Scott's announcement. I'll draw attention to one of them.  Earlier this year we wrote the initial version of a new UK Government web application called CloudStore.  CloudStore provides a way for local and central government to discover and purchase applications and services. We wrote the web site using ASP.NET MVC which is FOSS.  However, this point has been lost on the ladies and gentlemen of the press and, I suspect, on some of the decision makers on the government side.  They announced a few weeks ago that future versions of CloudStore will move to a FOSS framework, clearly oblivious of the fact that it is already built on a FOSS framework.  We are, it is fair to say, mildly irked by the uninformed and badly out-of-date assumption that “if it is Microsoft, it can't be FOSS”.  Old prejudices live on.

    Read the article

  • Mathemagics - 3 consecutive number

    - by PointsToShare
    © 2011 By: Dov Trietsch. All rights reserved Three Consecutive numbers When I was young and handsome (OK, OK, just young), my father used to challenge us with riddles and tricks involving Logic, Math and general knowledge. Most of the time, at least after reaching the ripe age of 10, I would see thru his tricks in no time. This one is a bit more subtle. I had to think about it for close to an hour and then when I had the ‘AHA!’ effect, I could not understand why it had taken me so long. So here it is. You select a volunteer from the audience (or a shill, but that would be cheating!) and ask him to select three consecutive numbers, all of them 1 or 2 digits. So {1, 2, 3} would be good, albeit trivial set, as would {8, 9, 10} or {97, 98, 99} but not {99, 99, 100} (why?!). Now, using a calculator – and these days almost every phone has a built in calculator – he is to perform these steps: 1.      Select a single digit 2.      Multiply it by 3 and write it down 3.      Add the 3 consecutive numbers 4.      Add the number from step 2 5.      Multiply the sum by 67 6.      Now tell me the last 2 digits of the result and also the number you wrote down in step 2 I will tell you which numbers you selected. How do I do this? I’ll give you the mechanical answer, but because I like you to have the pleasure of an ‘AHA!’ effect, I will not really explain the ‘why’. So let’s you selected 30, 31, and 32 and also that your 3 multiple was 24, so here is what you get 30 + 31 + 32 = 93 93 + 24 = 117 117 x 67 = 7839, last 2 digits are 39, so you say “the last 2 digits are 39, and the other number is 24.” Now, I divide 24 by 3 getting 8. I subtract 8 from 39 and get 31. I then subtract 1 from this getting 30, and say: “You selected 30, 31, and 32.” This is the ‘how’. I leave the ‘why’ to you! That’s all folks! PS do you really want to know why? Post a feedback below. When 11 people or more will have asked for it, I’ll add a link to the full explanation.

    Read the article

  • Increase application performance

    - by Prayos
    I'm writing a program for a company that will generate a daily report for them. All of the data that they use for this report is stored in a local SQLite database. For this report, the utilize pretty much every bit of the information in the database. So currently, when I query the datbase, I retrieve everything, and store the information in lists. Here's what I've got: using (var dataReader = _connection.Select(query)) { if (dataReader.HasRows) { while (dataReader.Read()) { _date.Add(Convert.ToDateTime(dataReader["date"])); _measured.Add(Convert.ToDouble(dataReader["measured_dist"])); _bit.Add(Convert.ToDouble(dataReader["bit_loc"])); _psi.Add(Convert.ToDouble(dataReader["pump_press"])); _time.Add(Convert.ToDateTime(dataReader["timestamp"])); _fob.Add(Convert.ToDouble(dataReader["force_on_bit"])); _torque.Add(Convert.ToDouble(dataReader["torque"])); _rpm.Add(Convert.ToDouble(dataReader["rpm"])); _pumpOneSpm.Add(Convert.ToDouble(dataReader["pump_1_strokes_pm"])); _pumpTwoSpm.Add(Convert.ToDouble(dataReader["pump_2_strokes_pm"])); _pullForce.Add(Convert.ToDouble(dataReader["pull_force"])); _gpm.Add(Convert.ToDouble(dataReader["flow"])); } } } I then utilize these lists for the calculations. Obviously, the more information that is in this database, the longer the initial query will take. I'm curious if there is a way to increase the performance of the query at all? Thanks for any and all help. EDIT One of the report rows is called Daily Drilling Hours. For this calculation, I use this method: // Retrieves the timestamps where measured depth == bit depth and PSI >= 50 public double CalculateDailyProjectDrillingHours(DateTime date) { var dailyTimeStamps = _time.Where((t, i) => _date[i].Equals(date) && _measured[i].Equals(_bit[i]) && _psi[i] >= 50).ToList(); return _dailyDrillingHours = Convert.ToDouble(Math.Round(TimeCalculations(dailyTimeStamps).TotalHours, 2, MidpointRounding.AwayFromZero)); } // Checks that the interval is less than 10, then adds the interval to the total time private static TimeSpan TimeCalculations(IList<DateTime> timeStamps) { var interval = new TimeSpan(0, 0, 10); var totalTime = new TimeSpan(); TimeSpan timeDifference; for (var j = 0; j < timeStamps.Count - 1; j++) { if (timeStamps[j + 1].Subtract(timeStamps[j]) <= interval) { timeDifference = timeStamps[j + 1].Subtract(timeStamps[j]); totalTime = totalTime.Add(timeDifference); } } return totalTime; }

    Read the article

< Previous Page | 409 410 411 412 413 414 415 416 417 418 419 420  | Next Page >