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  • Microphone doesn't work

    - by mandy
    I'm having a trouble with my built in microphone. Even if I use headphone with mic, it doesn't really work. The weird thing is, if I clap the green lines of the speaker icon jumps, but if I speak it doesn't. I have also tried some recordings, but I can not hear myself and adjusting the volume didn't help at all. I tried to restore it, still no change. I have updated it in the device manager, but it said there that it's up to date and the devices are working properly. Until I decided to recover the whole system (wherein I pressed zero and switch on button) to my surprise, the settings became different, most programs were deleted, even my files. It's like it was formatted and I'm so sad that the mic was not fixed. I really don't know what to do now. My laptop model is Toshiba satellite m840. I want to it return to its settings/set up just before I Recover the system and bring back all the programs that we're installed and of course, most of all, to fix my microphone so I can use Skype again and other video calling application.. I hope someone could help me. Thanks a lot!

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  • saving data from a failing drive

    - by intuited
    An external 3½" HDD seems to be in danger of failing — it's making ticking sounds when idle. I've acquired a replacement drive, and want to know the best strategy to get the data off of the dubious drive with the best chance of saving as much as possible. There are some directories that are more important than others. However, I'm guessing that picking and choosing directories is going to reduce my chances of saving the whole thing. I would also have to mount it, dump a file listing, and then unmount it in order to be able to effectively prioritize directories. Adding in the fact that it's time-consuming to do this, I'm leaning away from this approach. I've considered just using dd, but I'm not sure how it would handle read errors or other problems that might prevent only certain parts of the data from being rescued, or which could be overcome with some retries, but not so many that they endanger other parts of the drive from being saved. I guess ideally it would do a single pass to get as much as possible and then go back to retry anything that was missed due to errors. Is it possible that copying more slowly — e.g. pausing every x MB/GB — would be better than just running the operation full tilt, for example to avoid any overheating issues? For the "where is your backup" crowd: this actually is my backup drive, but it also contains some non-critical and bulky stuff, like music, that aren't backups, i.e. aren't backed up. The drive has not exhibited any clear signs of failure other than this somewhat ominous sound. I did have to fsck a few errors recently — orphaned inodes, incorrect free blocks/inodes counts, inode bitmap differences, zero dtime on deleted inodes; about 20 errors in all. The filesystem of the partition is ext3.

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  • How to make Thunderbird play nice with Google mail

    - by Christi
    Thunderbird and gmail aren't exactly the best of friends. Gmail's tags mean that Thunderbird often downloads multiple copies of a single mail. Anything tagged in gmail will appear in a folder related to that tag, the "all mail" folder, and possibly the "inbox" and "sent mail" folders too. Thus a mail with multiple tags could potentially be stored more than four times in a local Thunderbird cache. This can make searching difficult, and is obviously wasteful of disk space. The best solution I have come up with is as follows. Operate a zero inbox policy (i.e. use the inbox for processing live mail only and archive everything else) which eliminates an extra copy in the inbox. Secondly, configure Thunderbird not to sync the "Sent Mail" folder - this is a bit of a pain, since I actually find it quite useful to be able to look through just the mails I've sent, but a search can duplicate this functionality. In this way, most of the duplicates are removed, and only mail with tags is stored locally more than once. Ideally, however, I'd only like one copy of each mail to be stored locally. I am surprised Thunderbird doesn't store mail by some sort of hashing algorithm to prevent precisely this problem - but it wouldn't be compatible with the way the folders are mirrored in a local directory structure, I suppose. Can anyone think of a better way to get Thunderbird to cache a Google mail account locally efficiently.

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  • Outlook 2010 PST not indexing

    - by kellyllek
    I've had this problem for months: Outlook is unable to search recent items in the inbox. I was running Outlook 2010 Beta. I've just moved to the Trial version, hoping to solve the issue. I have tons of PST files but one central one I'm mainly concerned with. As of now it seems none of it is indexing. I've been through all the sites and made all the changes; rebuilt the index, changed the name of the PST files, run scanpst, stopped and started the search services, made sure the Windows features under programs and features has the indexing option checked, etc... Status now says 'zero items left to index', and 150,000 have been indexed. I think I have a lot more files than that, and also nothing is showing up on any search. I'm not sure what else to do? Side question. I'm going to be moving out of Outlook. However I have 10Gigs+ of PST files over the years. I want to merge them and make them search-able in the easiest way possible. Any idea on how to do that? Could I even move over to Thunderbird right now and be able to index and search my PST files? Also, Google Desktop won't index Outlook 2010 email either...

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  • Is there any way to shut up my ATI HD 5770?

    - by slpsys
    So to preface, I basically built Jeff's machine; I already had some of the components, including (scarily enough) the exact same case1. I've been buying bits and pieces over the past few months, which coincided perfectly with his recent post about three monitors, though not being a gamer outright, I opted for the second-from-the-bottom option. After finally plopping all the pieces lovingly into the case this evening, I turn it on...and it sounds like four professional grade hair-driers. Some quick regression analysis determined that with the video card out, the running machine sounded no louder than our house's vents. Basically, my last desktop build included a $45-at-the-time graphics card, and it's been Macbook Pros and workstations since then, so I have zero idea whether I'll just be able to tune the fan speed later on. Will I be able to get this thing to quiet down every time I'm not playing Modern Warfare 2 at maximum framerate, or should I just send this thing back now, and get the quietest card in my pricerange? 1 One thing of note is that I do not have noise-absorbing foam in the case, as is pictured in the article. I'm only mentioning that because I suspect it could drop the overall output a few decibels, but obviously not that many.

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  • What can be a reason for phpMyAdmin login to be not working (not at all, no reaction on submit)?

    - by Ivan
    When I open "http://localhost/phpmyadmin/", enter "root" as the user name and my MySQL root password and press go, then if I was using Firefox, I was getting offered to download index.php file (of a zero length), if I was using Opera 11, it said "Connection closed by remote server". Following recommendations I've removed all packages related to phpMyAdmin, PHP, MySQL and Apache and then reinstalled them step-by step (instead of just issuing apt-get install phpmyadmin and relying on the system to install the whole LAMP stack via dependencies as I've done before). The only change I've got was Firefox to stop offering to download index.php - now when I press Ok to submit my password, it just doesn't show any visible reaction at all. What may the reason be and how to fix it? I use up-to-date Xubuntu 11.04. Reinstalling the whole LAMP stack and phpMyAdmin did not help, neither did removing AppArmor. I've tried to use SQLBuddy instead, but there's exactly the same problem. So, I think, the problem is not in phpMyAdmin but in MySQL, Apache or something. MySQL seems to work if I use command line to access it. Apache & PHP seems to work also, as the login page of phpMyAdmin displays correctly.

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  • Relinking a deleted file

    - by mbac32768
    Sometimes people delete files they shouldn't, a long-running process still has the file open, and recovering the data by catting /proc/<pid>/fd/N just isn't awesome enough. Awesome enough would be if you could "undo" the delete by running some magic option to ln that would let you re-link to the inode number (recovered through lsof). I can't find any Linux tools to do this, least with cursory Googling. What do you got, serverfault? EDIT1: The reason catting the file from /proc/<pid>/fd/N isn't awesome enough is because the process which still has the file open is still writing to it. A delete removes the reference to the inode from the filesystem namespace. What I want is a way of re-creating the reference. EDIT2: 'debugfs ln' works but the risk is too high since it frobs raw filesystem data. The recovered file is also crazy inconsistent. The link count is zero and I can't add links to it. I'm worse off this way since I can just use /proc/<pid>/fd/N to access the data without corrupting my fs.

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  • Are there tools available for trimming PDF margins?

    - by Charles Duffy
    I have an ebook I'm trying to read in PDF format on a Kindle. Unfortunately, the page headers and footers have some content (page number and copyright info, respectively) preventing the device from scaling the actual text to match its usable area viewing area, thus leaving the actual content too small to read. Various tools are available which will trim off whitespace, but the Kindle already does this; my goal, by contrast, is to remove printed matter outside of a defined bounding box, and the only tool I've found for the purpose is moderately expensive commercial software. I could probably generate a mask in Inkscape; split out the individual pages using pdftk, apply the mask to each page individually (outputting to postscript), and recombine the numerous postscript files into a single PDF. However, this decode/reencode steps would be pretty unfortunate in terms of document size; something able to operate with a bit more finesse would be ideal. I have all major operating systems handy (Windows, several modern Linux distros, a Mac, etc) so solutions don't need to be constrained by platform. Suggestions? (I've reported the issue to the author, who mentioned it to his editor, who hasn't done anything about the issue over the course of more than a month, making the zero-work approach evidently nonproductive).

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  • Oracle: 1 Large Server vs. 2 Smaller Servers?

    - by nvahalik
    We are in the planning stages of setting up our production Oracle 10gR2 environment. Our budget gives us the ability to buy 2 processor licenses of Oracle DB Standard Edition. We have minimal experience with Oracle so I'll defer to anyone who has used it. We are trying to decide if we should set up a single dual quad-core box or 2 individual quad-core boxes in a RAC configuration. Our DB right now is about 60 GB, and at our peak, we'll have up to 150 concurrent users. Most of the big stuff is done via batch processing at night. My gut tells me that having 2 boxes in a RAC configuration can't be a bad thing because it provides a true hardware failover solution. DB stored in a shared LUN on a SAN via iSCSI. Plus if we ever need to add capacity, we already have boxes in place that can be upgraded with extra procs (I assume with zero downtime, since it's set up in a RAC config) if we add extra licenses, or RAM. Does RAC have any performance penalties? Will it add extra latency? Is there any true advantage for having dual processor boxes running these systems? If we build out the Oracle boxes with special hardware: hardware iSCSI cards, TOE NICs, will these boxes be solid? We are deploying on 64-bit Windows. So what would you do? One box or two?

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  • less maximum buffer size?

    - by Tyzoid
    I was messing around with my system and found a novel way to use up memory, but it seems that the less command only holds a limited amount of data before stopping/killing the command. To test, run (careful! uses lots of system memory very fast!) $ cat /dev/zero | less From my testing, it looks like the command is killed after less reaches 2.5 gigabytes of memory, but I can't find anything in the man page that suggests that it would limit it in such a way. In addition, I couldn't find any documentation via the google on the subject. Any light to this quite surprising discovery would be great! System Information: Quad core intel i7, 8gb ram. $ uname -a Linux Tyler-Work 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux $ less --version less 458 (GNU regular expressions) Copyright (C) 1984-2012 Mark Nudelman less comes with NO WARRANTY, to the extent permitted by law. For information about the terms of redistribution, see the file named README in the less distribution. Homepage: http://www.greenwoodsoftware.com/less $ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 14.04 LTS Release: 14.04 Codename: trusty

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  • Why is my rsync so slow?

    - by iblue
    My Laptop and my workstation are both connected to a Gigabit Switch. Both are running Linux. But when I copy files with rsync, it performs badly. I get about 22 MB/s. Shouldn't I theoretically get about 125 MB/s? What is the limiting factor here? EDIT: I conducted some experiments. Write performance on the laptop The laptop has a xfs filesystem with full disk encryption. It uses aes-cbc-essiv:sha256 cipher mode with 256 bits key length. Disk write performance is 58.8 MB/s. iblue@nerdpol:~$ LANG=C dd if=/dev/zero of=test.img bs=1M count=1024 1073741824 Bytes (1.1 GB) copied, 18.2735 s, 58.8 MB/s Read performance on the workstation The files I copied are on a software RAID-5 over 5 HDDs. On top of the raid is a lvm. The volume itself is encrypted with the same cipher. The workstation has a FX-8150 cpu that has a native AES-NI instruction set which speeds up encryption. Disk read performance is 256 MB/s (cache was cold). iblue@raven:/mnt/bytemachine/imgs$ dd if=backup-1333796266.tar.bz2 of=/dev/null bs=1M 10213172008 bytes (10 GB) copied, 39.8882 s, 256 MB/s Network performance I ran iperf between the two clients. Network performance is 939 Mbit/s iblue@raven $ iperf -c 94.135.XXX ------------------------------------------------------------ Client connecting to 94.135.XXX, TCP port 5001 TCP window size: 23.2 KByte (default) ------------------------------------------------------------ [ 3] local 94.135.XXX port 59385 connected with 94.135.YYY port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.09 GBytes 939 Mbits/sec

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  • AWS instance went down for restart, came back up and has been "Waiting for network configuration... " for 12 hours

    - by kavisiegel
    What happened was about a month ago, I created a new instance, re-configured everything, and mounted the old instances drive to the new one. I then detached the old drive from the instance, but it was still mounted, so it errored out. Now, come the outage last month, and when the instance boots back up - the drive isn't there, because in the downtime, it dismounted. It hangs because the fstab is looking for it. I get word that the server's not up today, I check the logs, re-attach the drive and restart. Now I'm getting "Waiting for network configuration..." and it doesn't seem to be doing anything. Some googling told me that I'm going to need to start from zero again, which I don't think is right. I created a new instance, which booted no problem, then I stopped it and swapped the two old drives into the new instance. Still the same error. Using the fresh AMI, it worked. I figure it's just a misconfigured Amazon file. I can attach the drive to a functioning instance on the same AMI and copy some files over, then try again - but I don't know where to even start or what files to check.

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  • Allied Telesis router: IP filtering for the LOCAL interface

    - by syneticon-dj
    Given an Allied Telesis router with an AlliedWare OS (2.9.1) I would like to disable access to all management services of the router except for a number of subnets (or alternatively have what is a "management VLAN" with other manufacturers' switch and router models). What I have tried so far: creating a new VLAN and an appropriate IP interface, setting the LOCAL IP into this subnet, creating an IP filter for the IP interface and specifying my exclusion subnets: it simply does not work as intended as I can access the LOCAL IP set from any of the other VLAN interfaces - the traffic is apparently not going through my defined filter set at all creating a new IP filter set and binding it to the LOCAL IP interface: this seems not to affect any kind of traffic at all, the counters for the filter set remain at zero packets setting the Remote Security Officer Level IP address range: this only restricts the ability for a user with the Security Officer privilege level to log in from any but the specified address ranges / subnets. Unfortunately, it does not prevent service availability (and thus DoS capacity) or the ability to log in as a less privileged user (e.g. a "manager") calling technical support: unfortunately no solution so far What I have not tried: creating a filter set for each and every IP interface defined on the router and excluding access to the router's management IP: I would like to reduce the overhead induced by IP filters as the router already is CPU-constrained at times. Setting up filters for every IP interface would mean that each and every traffic packet would have to pass the filters, thus consuming CPU cycles. If by any means possible, I would like to find a different solution.

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  • Driver corruption when deploying Dell Touchpad Drivers (with software) during imaging process

    - by BigHomie
    We're an sccm shop, and use it to deploy Windows. When deploying Dell laptops (multiple models), the touchpad drivers seem install properly, but the software doesn't. The resulting problem is that when the touchpad is pressed on occasion, the mouse pointer will 'jump' to certain points on the screen. A possible symptom of this problem/visible sign is if the touchpad icon isn't in the system tray. The software is in the control panel, but when opened part of the gui is pixelated, indicating botched install maybe? The manual resolution to this, is to go into device manager and uninstall the driver with the option to uninstall all driver software. After a restart, the driver and software is apparently reinstalled, and from there works as expected. Obviously this partially defeats the purpose of a zero touch deployment. If anyone knows why this is and/or a possible workaround, those answers would be valid as well. Barring that, I want to find a way to deploy the driver and touchpad software in an unattended way, so that it can be conditionally installing during the imaging process. To be honest I'm not sure how to troubleshoot this, I suppose I could try drvinst.exe to install the driver, but finding out why this fails initially would keep me from spinning my wheels.

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  • Non-restored Files Corrupted on System Restore

    - by Yar
    I restored OSX 10.6.2 today (was 10.6.3 and not booting) by copying the system over from a backup. The data directories were not touched. In the data directories, I'm seeing some files as 0 bytes, and getting permission-denied errors when copying, even when using sudo cp or the Finder itself. Some programs, differently, take the files at face value and see no permission problems (such as zip), but they see the files as zero bytes, which would be game-over for recovery. cp: .git/objects/fe/86b676974a44aa7f128a55bf27670f4a1073ca: could not copy extended attributes to /eraseme/blah/.git/objects/fe/86b676974a44aa7f128a55bf27670f4a1073ca: Operation not permitted I have tried sudo chown, sudo chmod -R 777 and sudo chflags -R nouchg which do not change the end result. Strangely, this is only affecting my .git directories (perhaps because they start with a period, but renaming them -- which works -- does not change anything). What else can I do to take ownership of these files? Edit: This question comes from StackOverflow because I originally thought it was a GIT problem. It's definitely not (just) GIT. Anyway, this is to help put some of the comments in context.

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  • Reverse NAT Setup for Hyper-V on Win 2008 R2

    - by sukru
    I'm trying to setup a Linux server behind a Windows Hyper-V host that will help supply some of the services (SSH, HTTPS, etc). However getting RRAS configured for reverse NAT (port forwarding) turned out to be a non trivial task. As a staring point, I tried forwarding port 22 (SSH) to the virtual machine. The virtual machine is on a public interface (i.e.: it also has a visible IP on the same network as the host). On RRAS management console I tried to add a rule, by adding "Local Area Connection" to NAT pool (Public Interface - Enable Nat), and an incoming rule for port 22 - :22. I also tried with the same port enabled on Windows Firewall (and not). The NAT management page tells there are "1 mappings" and "30+ Outbound packets transleted". However all other counters (Inbound packets translated, and respective rejected ones) are always zero. (I'm trying to access the server from an external machine). I can directly access the service if I give the VM's public IP, but not the host's one. Is there a way to enable this on RRAS?

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  • Users Password does not reset after successful login at the console but works fine with SSH

    - by jnbbender
    The title says it all. I have my unsuccessful login attempts set to three. I purposefully fail logging in 2x, then when I SSH into the box successfully the 3rd time my count drops back to zero; exactly what should happen. But at the console I get failed login attempts EVEN for my successful login attempts. I am using RHEL 5.6 and no I am not able to upgrade. Here is my system-auth file: auth required pam_env.so auth required pam_tally.so onerr=fail deny=3 per_user auth sufficient pam_unix.so nullok try_first_pass auth requisite pam_succeed_if.so uid >= 500 quiet auth required pam_deny.so account required pam_unix.so account required pam_tally.so account sufficient pam_succeed_if.so uid < 500 quiet account required pam_permit.so password requisite pam_cracklib.so try_first_pass retry=3 password sufficient pam_unix.so md5 shadow nullok try_first_pass use_authtok password required pam_deny.so session optional pam_keyinit.co revoke session required pam_limits.so session [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid session required pam_unix.so I have tried adding reset after and in place of per_user in the auth required pam_tally.so field. Nothing seems to work and I don't know why SSH is working just fine. Any ideas?

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  • Using iptables to make a VPN router

    - by lost_in_the_sauce
    I am attempting to make a VPN connection to a third party VPN site, then forward traffic from my internal computers (ssh and ping for now) out to the VPN site using IPTables. 3rd Party <- (tun0/eth0)Linux VPN Box(eth1) <- Windows7TestBox I am running on CentOS 6.3 Linux and have two network connections eth0-public eth1-private. I am running vpnc-0.5.3-4 which is currently connecting to my destination. When I connect I am able to ping the destination IPAddresses but that is as far as I can get. ping -I tun0 10.1.33.26 success ping -I eth0 10.1.33.26 fail ping -I eth1 10.1.33.26 fail I have my private network Windows 7 test box set up to have the eth1 (private) network of my VPN Server as its gateway and can ping him fine. I need IPTables to send the Windows 7 traffic out the VPN tunnel. I have tried for a few days many different IPTables configurations from this site and others, either the other examples are too simple or overly complicated. The only thing this server is doing is connecting to the VPN and forwarding all traffic. So we can "flush" everything and start from scratch here. It is a blank slate. #!/bin/bash echo "Define variables" ipt="/sbin/iptables" echo "Zero out all counters" $ipt -Z $ipt -t nat -Z $ipt -t mangle -Z echo "Flush all active rules, delete all chains" $ipt -F $ipt -X $ipt -t nat -F $ipt -t nat -X $ipt -t mangle -F $ipt -t mangle -X $ipt -P INPUT ACCEPT $ipt -P FORWARD ACCEPT $ipt -P OUTPUT ACCEPT $ipt -t nat -A POSTROUTING -o tun0 -j MASQUERADE $ipt -A FORWARD -i eth1 -o eth0 -j ACCEPT $ipt -A FORWARD -i eth0 -o eth1 -j ACCEPT $ipt -A FORWARD -i eth0 -o tun0 -j ACCEPT $ipt -A FORWARD -i tun0 -o eth0 -j ACCEPT Again I have done many variations of the above and many other rules from other posts but haven't been able to move forward. It seems like such a simple task, and yet....

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  • How to reduce memory consumption an AWS EC2 t1.micro instance (free tier) ubuntu server 14.04 LTS EBS

    - by CMPSoares
    Hi I'm working on my bachelor thesis and for that I need to host a node.js web application on AWS, in order to avoid costs I'm using a t1.micro instance with 30GB disk space (from what I know it's the maximum I get in the free tier) which is barely used. But instead I have problems with memory consumption, it's using all of it. I tried the approach of creating a virtual swap area as mentioned at Why don't EC2 ubuntu images have swap? with these commands: sudo dd if=/dev/zero of=/var/swapfile bs=1M count=2048 && sudo chmod 600 /var/swapfile && sudo mkswap /var/swapfile && echo /var/swapfile none swap defaults 0 0 | sudo tee -a /etc/fstab && sudo swapon -a But this swap area isn't used somehow. Is something missing in this approach or is there another process of reducing the memory consumption in these type of AWS instances? Bottom-line: This originates server freezes and crashes and that's what I want to stop either by using the swap, reducing memory usage or both.

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  • Tungsten for MySQL: Online Schema Upgrade

    - by Jason
    In a recent presentation the Continuent folks claim that they support "daylight maintenance" or online schema upgrades. See Clustering for the Masses: A Gentle Introduction to Tungsten for MySQL, especially pages 22-28. Is anyone using Tungsten for MySQL in this way? It sounds too good to be true. I also wonder if the Community Edition supports all of the features discussed in the presentation. They say elsewhere that it is not crippleware but in their own productization table "Zero downtime upgrade" appears to only be available in the more advanced versions. So I'm skeptical. Community support seems rather non-existent so a commercial license with support is probably warranted (they do not disclose pricing). I have not contacted them directly yet as I prefer community vetting but this solution, despite its value proposition and power to make an admin's life easier just doesn't seem to get the kind of attention it might warrant. If not Tungsten for MySQL, how do you handle online schema upgrades? MySQL Cluster (NDBENGINE) is not well-suited to web applications. Cheers

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  • How to ensure local file is up-to-date or ahead (dropbox sync) before truecrypt auto-mount it?

    - by user620965
    There are a lot tutorials out there that states that dropbox build-in encryption is not secure enought. That tutorials recommands to sync a truecrypt container file to have all files in it securely encrypted. This setup is know to be limited. You can NOT have that truecrypt container file mounted on the same time on more than one location - if you have inserted changes to the contents of the container in more then one location at a time then this setup produces a conflict on the container file in the dropbox system - resulting in one container file for each location. In my case that issue is not relevant - i do not use my data on more than one location at a time. I want to use the auto-mount feature of truecrypt on startup of windows 7 to have a zero configuration environment - and start working right away. But i want to ensure that the local truecrypt container file is up-to-date before truecrypt mounts it automatically - imagine you updated the contents of the container on your primary location and your secondary location was off for a long time. In that case it can take "a long time" till dropbox sync is complete (e.g. depending on your internet connection and the size of the container file). There is a option in truecrypt that ensures that truecrypt do not update the timestamp of the container file - which speeds up the sync, because dropbox client is doing a differential sync then instead of a time consuming full-sync. That is an improvement to that setup, but this do not fix my issue. The question is how to make the auto-mount function wait for the container file to be up-to-date (updated by dropbox)? In contrast: if the file was changed local, but remote file (in the dropbox cloud system) is still old (not jet updated by the sync process / or process is progress), should not make truecrypt to wait for the sync. Suggestions?

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  • What approach to take for SIMD optimizations

    - by goldenmean
    Hi, I am trying to optimize below code for SIMD operations (8way/4way/2way SIMD whiechever possible and if it gives gains in performance) I am tryin to analyze it first on paper to understand the algorithm used. How can i optimize it for SIMD:- void idct(uint8_t *dst, int stride, int16_t *input, int type) { int16_t *ip = input; uint8_t *cm = ff_cropTbl + MAX_NEG_CROP; int A, B, C, D, Ad, Bd, Cd, Dd, E, F, G, H; int Ed, Gd, Add, Bdd, Fd, Hd; int i; /* Inverse DCT on the rows now */ for (i = 0; i < 8; i++) { /* Check for non-zero values */ if ( ip[0] | ip[1] | ip[2] | ip[3] | ip[4] | ip[5] | ip[6] | ip[7] ) { A = M(xC1S7, ip[1]) + M(xC7S1, ip[7]); B = M(xC7S1, ip[1]) - M(xC1S7, ip[7]); C = M(xC3S5, ip[3]) + M(xC5S3, ip[5]); D = M(xC3S5, ip[5]) - M(xC5S3, ip[3]); Ad = M(xC4S4, (A - C)); Bd = M(xC4S4, (B - D)); Cd = A + C; Dd = B + D; E = M(xC4S4, (ip[0] + ip[4])); F = M(xC4S4, (ip[0] - ip[4])); G = M(xC2S6, ip[2]) + M(xC6S2, ip[6]); H = M(xC6S2, ip[2]) - M(xC2S6, ip[6]); Ed = E - G; Gd = E + G; Add = F + Ad; Bdd = Bd - H; Fd = F - Ad; Hd = Bd + H; /* Final sequence of operations over-write original inputs. */ ip[0] = (int16_t)(Gd + Cd) ; ip[7] = (int16_t)(Gd - Cd ); ip[1] = (int16_t)(Add + Hd); ip[2] = (int16_t)(Add - Hd); ip[3] = (int16_t)(Ed + Dd) ; ip[4] = (int16_t)(Ed - Dd ); ip[5] = (int16_t)(Fd + Bdd); ip[6] = (int16_t)(Fd - Bdd); } ip += 8; /* next row */ } ip = input; for ( i = 0; i < 8; i++) { /* Check for non-zero values (bitwise or faster than ||) */ if ( ip[1 * 8] | ip[2 * 8] | ip[3 * 8] | ip[4 * 8] | ip[5 * 8] | ip[6 * 8] | ip[7 * 8] ) { A = M(xC1S7, ip[1*8]) + M(xC7S1, ip[7*8]); B = M(xC7S1, ip[1*8]) - M(xC1S7, ip[7*8]); C = M(xC3S5, ip[3*8]) + M(xC5S3, ip[5*8]); D = M(xC3S5, ip[5*8]) - M(xC5S3, ip[3*8]); Ad = M(xC4S4, (A - C)); Bd = M(xC4S4, (B - D)); Cd = A + C; Dd = B + D; E = M(xC4S4, (ip[0*8] + ip[4*8])) + 8; F = M(xC4S4, (ip[0*8] - ip[4*8])) + 8; if(type==1){ //HACK E += 16*128; F += 16*128; } G = M(xC2S6, ip[2*8]) + M(xC6S2, ip[6*8]); H = M(xC6S2, ip[2*8]) - M(xC2S6, ip[6*8]); Ed = E - G; Gd = E + G; Add = F + Ad; Bdd = Bd - H; Fd = F - Ad; Hd = Bd + H; /* Final sequence of operations over-write original inputs. */ if(type==0){ ip[0*8] = (int16_t)((Gd + Cd ) >> 4); ip[7*8] = (int16_t)((Gd - Cd ) >> 4); ip[1*8] = (int16_t)((Add + Hd ) >> 4); ip[2*8] = (int16_t)((Add - Hd ) >> 4); ip[3*8] = (int16_t)((Ed + Dd ) >> 4); ip[4*8] = (int16_t)((Ed - Dd ) >> 4); ip[5*8] = (int16_t)((Fd + Bdd ) >> 4); ip[6*8] = (int16_t)((Fd - Bdd ) >> 4); }else if(type==1){ dst[0*stride] = cm[(Gd + Cd ) >> 4]; dst[7*stride] = cm[(Gd - Cd ) >> 4]; dst[1*stride] = cm[(Add + Hd ) >> 4]; dst[2*stride] = cm[(Add - Hd ) >> 4]; dst[3*stride] = cm[(Ed + Dd ) >> 4]; dst[4*stride] = cm[(Ed - Dd ) >> 4]; dst[5*stride] = cm[(Fd + Bdd ) >> 4]; dst[6*stride] = cm[(Fd - Bdd ) >> 4]; }else{ dst[0*stride] = cm[dst[0*stride] + ((Gd + Cd ) >> 4)]; dst[7*stride] = cm[dst[7*stride] + ((Gd - Cd ) >> 4)]; dst[1*stride] = cm[dst[1*stride] + ((Add + Hd ) >> 4)]; dst[2*stride] = cm[dst[2*stride] + ((Add - Hd ) >> 4)]; dst[3*stride] = cm[dst[3*stride] + ((Ed + Dd ) >> 4)]; dst[4*stride] = cm[dst[4*stride] + ((Ed - Dd ) >> 4)]; dst[5*stride] = cm[dst[5*stride] + ((Fd + Bdd ) >> 4)]; dst[6*stride] = cm[dst[6*stride] + ((Fd - Bdd ) >> 4)]; } } else { if(type==0){ ip[0*8] = ip[1*8] = ip[2*8] = ip[3*8] = ip[4*8] = ip[5*8] = ip[6*8] = ip[7*8] = ((xC4S4 * ip[0*8] + (IdctAdjustBeforeShift<<16))>>20); }else if(type==1){ dst[0*stride]= dst[1*stride]= dst[2*stride]= dst[3*stride]= dst[4*stride]= dst[5*stride]= dst[6*stride]= dst[7*stride]= cm[128 + ((xC4S4 * ip[0*8] + (IdctAdjustBeforeShift<<16))>>20)]; }else{ if(ip[0*8]){ int v= ((xC4S4 * ip[0*8] + (IdctAdjustBeforeShift<<16))>>20); dst[0*stride] = cm[dst[0*stride] + v]; dst[1*stride] = cm[dst[1*stride] + v]; dst[2*stride] = cm[dst[2*stride] + v]; dst[3*stride] = cm[dst[3*stride] + v]; dst[4*stride] = cm[dst[4*stride] + v]; dst[5*stride] = cm[dst[5*stride] + v]; dst[6*stride] = cm[dst[6*stride] + v]; dst[7*stride] = cm[dst[7*stride] + v]; } } } ip++; /* next column */ dst++; } }

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  • C code won't compile

    - by cc
    Please help me to understand why the following code will not compile: #include <stdio.h> //#include <iostream> //using namespace std; int main(void){ int i,k,x,y,run,e,r,s,m,count=0; char numbers[19][19]; for(i=0;i<19;i++){ for (k=0;k<19;k++){ numbers[i][k]='.'; } } void drawB(){ printf(" 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 \n"); printf ("0 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[0][0],numbers[0][1],numbers[0][2],numbers[0][3],numbers[0][4], numbers[0][5],numbers[0][6],numbers[0][7],numbers[0][8],numbers[0][9], numbers[0][10],numbers[1][11],numbers[1][12],numbers[1][13],numbers[0][14] ,numbers[0][15],numbers[0][16],numbers[0][17],numbers[0][18]); printf ("1 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[1][0],numbers[1][1],numbers[1][2],numbers[1][3],numbers[1][4], numbers[1][5],numbers[1][6],numbers[1][7],numbers[1][8],numbers[1][9], numbers[1][10],numbers[1][11],numbers[1][12],numbers[1][13],numbers[1][14] ,numbers[1][15],numbers[1][16],numbers[1][17],numbers[1][18]); printf ("2 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" numbers[2][0],numbers[2][1],numbers[2][2],numbers[2][3],numbers[2][4], numbers[2][5],numbers[2][6],numbers[2][7],numbers[2][8],numbers[2][9], numbers[2][10],numbers[2][11],numbers[2][12],numbers[2][13],numbers[2][14] ,numbers[2][15],numbers[2][16],numbers[2][17],numbers[2][18]); printf ("3 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[3][0],numbers[3][1],numbers[3][2],numbers[3][3],numbers[3][4], numbers[3][5],numbers[3][6],numbers[3][7],numbers[3][8],numbers[3][9], numbers[3][10],numbers[3][11],numbers[3][12],numbers[3][13],numbers[3][14] ,numbers[3][15],numbers[3][16],numbers[3][17],numbers[3][18]); printf ("4 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[4][0],numbers[4][1],numbers[4][2],numbers[4][3],numbers[4][4], numbers[4][5],numbers[4][6],numbers[4][7],numbers[4][8],numbers[4][9], numbers[4][10],numbers[4][11],numbers[4][12],numbers[4][13],numbers[4][14] ,numbers[4][15],numbers[4][16],numbers[4][17],numbers[4][18]); printf ("5 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[5][0],numbers[5][1],numbers[5][2],numbers[5][3],numbers[5][4], numbers[5][5],numbers[5][6],numbers[5][7],numbers[5][8],numbers[5][9], numbers[5][10],numbers[5][11],numbers[5][12],numbers[5][13],numbers[5][14] ,numbers[5][15],numbers[5][16],numbers[5][17],numbers[5][18]); printf ("6 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[6][0],numbers[6][1],numbers[6][2],numbers[6][3],numbers[6][4], numbers[6][5],numbers[6][6],numbers[6][7],numbers[6][8],numbers[6][9], numbers[6][10],numbers[6][11],numbers[6][12],numbers[6][13],numbers[6][14] ,numbers[6][15],numbers[6][16],numbers[6][17],numbers[6][18]); printf ("7 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[7][0],numbers[7][1],numbers[7][2],numbers[7][3],numbers[7][4], numbers[7][5],numbers[7][6],numbers[7][7],numbers[7][8],numbers[7][9], numbers[7][10],numbers[7][11],numbers[7][12],numbers[7][13],numbers[7][14] ,numbers[7][15],numbers[7][16],numbers[7][17],numbers[7][18]); printf ("8 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[8][0],numbers[8][1],numbers[8][2],numbers[8][3],numbers[8][4], numbers[8][5],numbers[8][6],numbers[8][7],numbers[8][8],numbers[8][9], numbers[8][10],numbers[8][11],numbers[8][12],numbers[8][13],numbers[8][14] ,numbers[8][15],numbers[8][16],numbers[8][17],numbers[8][18]); printf ("9 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[9][0],numbers[9][1],numbers[9][2],numbers[9][3],numbers[9][4], numbers[9][5],numbers[9][6],numbers[9][7],numbers[9][8],numbers[9][9], numbers[9][10],numbers[9][11],numbers[9][12],numbers[9][13],numbers[9][14] ,numbers[9][15],numbers[9][16],numbers[9][17],numbers[9][18]); printf ("0 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[10][0],numbers[10][1],numbers[10][2],numbers[10][3],numbers[10][4], numbers[10][5],numbers[10][6],numbers[10][7],numbers[10][8],numbers[10][9], numbers[10][10],numbers[10][11],numbers[10][12],numbers[10][13],numbers[10][14] ,numbers[10][15],numbers[10][16],numbers[10][17],numbers[10][18]); printf ("1 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[11][0],numbers[11][1],numbers[11][2],numbers[11][3],numbers[11][4], numbers[11][5],numbers[11][6],numbers[11][7],numbers[11][8],numbers[11][9], numbers[11][10],numbers[11][11],numbers[11][12],numbers[11][13],numbers[11][14] ,numbers[11][15],numbers[11][16],numbers[11][17],numbers[11][18]); printf ("2 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[12][0],numbers[12][1],numbers[12][2],numbers[12][3],numbers[12][4], numbers[12][5],numbers[12][6],numbers[12][7],numbers[12][8],numbers[12][9], numbers[12][10],numbers[12][11],numbers[12][12],numbers[12][13],numbers[12][14] ,numbers[12][15],numbers[12][16],numbers[12][17],numbers[12][18]); printf ("3 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[13][0],numbers[13][1],numbers[13][2],numbers[13][3],numbers[13][4], numbers[13][5],numbers[13][6],numbers[13][7],numbers[13][8],numbers[13][9], numbers[13][10],numbers[13][11],numbers[13][12],numbers[13][13],numbers[13][14] ,numbers[13][15],numbers[13][16],numbers[13][17],numbers[13][18]); printf ("4 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[14][0],numbers[14][1],numbers[14][2],numbers[14][3],numbers[14][4], numbers[14][5],numbers[14][6],numbers[14][7],numbers[14][8],numbers[14][9], numbers[14][10],numbers[14][11],numbers[14][12],numbers[14][13],numbers[14][14] ,numbers[14][15],numbers[14][16],numbers[14][17],numbers[14][18]); printf ("5 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[15][0],numbers[15][1],numbers[15][2],numbers[15][3],numbers[15][4], numbers[15][5],numbers[15][6],numbers[15][7],numbers[15][8],numbers[15][9], numbers[15][10],numbers[15][11],numbers[15][12],numbers[15][13],numbers[15][14] ,numbers[15][15],numbers[15][16],numbers[15][17],numbers[15][18]); printf ("6 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[16][0],numbers[16][1],numbers[16][2],numbers[16][3],numbers[16][4], numbers[16][5],numbers[16][6],numbers[16][7],numbers[16][8],numbers[16][9], numbers[16][10],numbers[16][11],numbers[16][12],numbers[16][13],numbers[16][14] ,numbers[16][15],numbers[16][16],numbers[16][17],numbers[16][18]); printf ("7 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[17][0],numbers[17][1],numbers[17][2],numbers[17][3],numbers[17][4], numbers[17][5],numbers[17][6],numbers[17][7],numbers[17][8],numbers[17][9], numbers[17][10],numbers[17][11],numbers[17][12],numbers[17][13],numbers[17][14] ,numbers[17][15],numbers[17][16],numbers[17][17],numbers[17][18]); printf ("8 %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c %c \n\n" ,numbers[18][0],numbers[18][1],numbers[18][2],numbers[18][3],numbers[18][4], numbers[18][5],numbers[18][6],numbers[18][7],numbers[18][8],numbers[18][9], numbers[18][10],numbers[18][11],numbers[18][12],numbers[18][13],numbers[18][14] ,numbers[18][15],numbers[18][16],numbers[18][17],numbers[18][18]); } void checkSurrounded (int x,int y){ //numbers [x-1,y-1 ] , numbers [x-1,y ] , numbers [x-1,y+1 ] //numbers [x,y-1 ] , numbers [x,y ] , numbers [x,y+1 ] //numbers [x+1,y-1, ] , numbers [x+1,y ] , numbers [x+1,y+1 ] if(numbers[x][y]=='A'){ if((numbers[x-1][y-1]=='B') && (numbers[x-1][y]=='B') && (numbers[x-1][y+1]=='B') && (numbers[x][y-1]=='B') && (numbers[x][y+1]=='B') && (numbers[x+1][y-1]=='B') && (numbers[x+1][y]=='B')){ numbers[x][y]='B';} } if(numbers[x][y]=='B'){ if((numbers[x-1][y-1]=='A') && (numbers[x-1][y]=='A') && (numbers[x-1][y+1]=='A') && (numbers[x][y-1]=='A') && (numbers[x][y+1]=='A') && (numbers[x+1][y-1]=='A') && (numbers[x+1][y]=='A')){ numbers[x][y]='A'; } } } /** void checkArea(){ //detect enemy stone //store in array //find adjacent enemy stones // store the enemy stones in the array //keep on doing this until there are no more enemy stones that are adjacent for (s=0;s<19;s++) { for (m=0;m<19;m++) { if (numbers[s][m]=='A'){ count++; } } } }//end fn void checkAdjacent(int x, int y){ if (numbers [x][y]=='A'){ if((numbers[x][y-1]=='B' && numbers [x-1][y]=='B' && numbers[x][y+1]=='B' && numbers[x+1][y]=='B')){ } } } void getUserInput(){ int run=1; while(run){ printf("Enter x coordinate\n"); scanf("%d",&x); printf("Enter y coordinate\n"); scanf("%d",&y); if((x>18 || y>18 || x<0 || y<0) && !( numbers[x][y]=='.' )){ printf("invalid imput\n"); } else{ numbers[x][y]='B'; run=0; drawB(); } } } */ void getCupInput(){ //go through borad //starting from [0][0] //stop at first player stone //save as target x and target y //surround target x and target y //if already surrounded //start looking in borad again from last position //at end of board reset to [0][0] for(s=0;s<19;s++) { for(m=0;m<19;m++) { if (numbers[s][m]==0){ count++; } } } x=x-2; y=y+2; numbers[x][y]='A'; drawB(); } while(1){ //getUserInput(); getCupInput(); } system("pause"); return 0; }

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  • Some problems with GridView in webpart with multiple filters.

    - by NF_81
    Hello, I'm currently working on a highly configurable Database Viewer webpart for WSS 3.0 which we are going to need for several customized sharepoint sites. Sorry in advance for the large wall of text, but i fear it's necessary to recap the whole issue. As background information and to describe my problem as good as possible, I'll start by telling you what the webpart shall do: Basically the webpart contains an UpdatePanel, which contains a GridView and an SqlDataSource. The select-query the Datasource uses can be set via webbrowseable properties or received from a consumer method from another webpart. Now i wanted to add a filtering feature to the webpart, so i want a dropdownlist in the headerrow for each column that should be filterable. As the select-query is completely dynamic and i don't know at design time which columns shall be filterable, i decided to add a webbrowseable property to contain an xml-formed string with filter information. So i added the following into OnRowCreated of the gridview: void gridView_RowCreated(object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.Header) { for (int i = 0; i < e.Row.Cells.Count; i++) { if (e.Row.Cells[i].GetType() == typeof(DataControlFieldHeaderCell)) { string headerText = ((DataControlFieldHeaderCell)e.Row.Cells[i]).ContainingField.HeaderText; // add sorting functionality if (_allowSorting && !String.IsNullOrEmpty(headerText)) { Label l = new Label(); l.Text = headerText; l.ForeColor = Color.Blue; l.Font.Bold = true; l.ID = "Header" + i; l.Attributes["title"] = "Sort by " + headerText; l.Attributes["onmouseover"] = "this.style.cursor = 'pointer'; this.style.color = 'red'"; l.Attributes["onmouseout"] = "this.style.color = 'blue'"; l.Attributes["onclick"] = "__doPostBack('" + panel.UniqueID + "','SortBy$" + headerText + "');"; e.Row.Cells[i].Controls.Add(l); } // check if this column shall be filterable if (!String.IsNullOrEmpty(filterXmlData)) { XmlNode columnNode = GetColumnNode(headerText); if (columnNode != null) { string dataValueField = columnNode.Attributes["DataValueField"] == null ? "" : columnNode.Attributes["DataValueField"].Value; string filterQuery = columnNode.Attributes["FilterQuery"] == null ? "" : columnNode.Attributes["FilterQuery"].Value; if (!String.IsNullOrEmpty(dataValueField) && !String.IsNullOrEmpty(filterQuery)) { SqlDataSource ds = new SqlDataSource(_conStr, filterQuery); DropDownList cbx = new DropDownList(); cbx.ID = "FilterCbx" + i; cbx.Attributes["onchange"] = "__doPostBack('" + panel.UniqueID + "','SelectionChange$" + headerText + "$' + this.options[this.selectedIndex].value);"; cbx.Width = 150; cbx.DataValueField = dataValueField; cbx.DataSource = ds; cbx.DataBound += new EventHandler(cbx_DataBound); cbx.PreRender += new EventHandler(cbx_PreRender); cbx.DataBind(); e.Row.Cells[i].Controls.Add(cbx); } } } } } } } GetColumnNode() checks in the filter property, if there is a node for the current column, which contains information about the Field the DropDownList should bind to, and the query for filling in the items. In cbx_PreRender() i check ViewState and select an item in case of a postback. In cbx_DataBound() i just add tooltips to the list items as the dropdownlist has a fixed width. Previously, I used AutoPostback and SelectedIndexChanged of the DDL to filter the grid, but to my disappointment it was not always fired. Now i check __EVENTTARGET and __EVENTARGUMENT in OnLoad and call a function when the postback event was due to a selection change in a DDL: private void FilterSelectionChanged(string columnName, string selectedValue) { columnName = "[" + columnName + "]"; if (selectedValue.IndexOf("--") < 0 ) // "-- All --" selected { if (filter.ContainsKey(columnName)) filter[columnName] = "='" + selectedValue + "'"; else filter.Add(columnName, "='" + selectedValue + "'"); } else { filter.Remove(columnName); } gridView.PageIndex = 0; } "filter" is a HashTable which is stored in ViewState for persisting the filters (got this sample somewhere on the web, don't remember where). In OnPreRender of the webpart, i call a function which reads the ViewState and apply the filterExpression to the datasource if there is one. I assume i had to place it here, because if there is another postback (e.g. for sorting) the filters are not applied any more. private void ApplyGridFilter() { string args = " "; int i = 0; foreach (object key in filter.Keys) { if (i == 0) args = key.ToString() + filter[key].ToString(); else args += " AND " + key.ToString() + filter[key].ToString(); i++; } dataSource.FilterExpression = args; ViewState.Add("FilterArgs", filter); } protected override void OnPreRender(EventArgs e) { EnsureChildControls(); if (WebPartManager.DisplayMode.Name == "Edit") { errMsg = "Webpart in Edit mode..."; return; } if (useWebPartConnection == true) // get select-query from consumer webpart { if (provider != null) { dataSource.SelectCommand = provider.strQuery; } } try { int currentPageIndex = gridView.PageIndex; if (!String.IsNullOrEmpty(m_SortExpression)) { gridView.Sort("[" + m_SortExpression + "]", m_SortDirection); } gridView.PageIndex = currentPageIndex; // for some reason, the current pageindex resets after sorting ApplyGridFilter(); gridView.DataBind(); } catch (Exception ex) { Functions.ShowJavaScriptAlert(Page, ex.Message); } base.OnPreRender(e); } So i set the filterExpression and the call DataBind(). I don't know if this is ok on this late stage.. don't have a lot of asp.net experience after all. If anyone can suggest a better solution, please give me a hint. This all works great so far, except when i have two or more filters and set them to a combination that returns zero records. Bam ... gridview gone, completely - without a possiblity of changing the filters back. So i googled and found out that i have to subclass gridview in order to always show the headerrow. I found this solution and implemented it with some modifications. The headerrow get's displayed and i can change the filters even if the returned result contains no rows. But finally to my current problem: When i have two or more filters set which return zero rows, and i change back one filter to something that should return rows, the gridview remains empty (although the pager is rendered). I have to completly refresh the page to reset the filters. When debugging, i can see in the overridden CreateChildControls of the grid, that the base method indeed returns 0, but anyway... the gridView.RowCount remains 0 after databinding. Anyone have an idea what's going wrong here?

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  • Project Euler #15

    - by Aistina
    Hey everyone, Last night I was trying to solve challenge #15 from Project Euler: Starting in the top left corner of a 2×2 grid, there are 6 routes (without backtracking) to the bottom right corner. How many routes are there through a 20×20 grid? I figured this shouldn't be so hard, so I wrote a basic recursive function: const int gridSize = 20; // call with progress(0, 0) static int progress(int x, int y) { int i = 0; if (x < gridSize) i += progress(x + 1, y); if (y < gridSize) i += progress(x, y + 1); if (x == gridSize && y == gridSize) return 1; return i; } I verified that it worked for a smaller grids such as 2×2 or 3×3, and then set it to run for a 20×20 grid. Imagine my surprise when, 5 hours later, the program was still happily crunching the numbers, and only about 80% done (based on examining its current position/route in the grid). Clearly I'm going about this the wrong way. How would you solve this problem? I'm thinking it should be solved using an equation rather than a method like mine, but that's unfortunately not a strong side of mine. Update: I now have a working version. Basically it caches results obtained before when a n×m block still remains to be traversed. Here is the code along with some comments: // the size of our grid static int gridSize = 20; // the amount of paths available for a "NxM" block, e.g. "2x2" => 4 static Dictionary<string, long> pathsByBlock = new Dictionary<string, long>(); // calculate the surface of the block to the finish line static long calcsurface(long x, long y) { return (gridSize - x) * (gridSize - y); } // call using progress (0, 0) static long progress(long x, long y) { // first calculate the surface of the block remaining long surface = calcsurface(x, y); long i = 0; // zero surface means only 1 path remains // (we either go only right, or only down) if (surface == 0) return 1; // create a textual representation of the remaining // block, for use in the dictionary string block = (gridSize - x) + "x" + (gridSize - y); // if a same block has not been processed before if (!pathsByBlock.ContainsKey(block)) { // calculate it in the right direction if (x < gridSize) i += progress(x + 1, y); // and in the down direction if (y < gridSize) i += progress(x, y + 1); // and cache the result! pathsByBlock[block] = i; } // self-explanatory :) return pathsByBlock[block]; } Calling it 20 times, for grids with size 1×1 through 20×20 produces the following output: There are 2 paths in a 1 sized grid 0,0110006 seconds There are 6 paths in a 2 sized grid 0,0030002 seconds There are 20 paths in a 3 sized grid 0 seconds There are 70 paths in a 4 sized grid 0 seconds There are 252 paths in a 5 sized grid 0 seconds There are 924 paths in a 6 sized grid 0 seconds There are 3432 paths in a 7 sized grid 0 seconds There are 12870 paths in a 8 sized grid 0,001 seconds There are 48620 paths in a 9 sized grid 0,0010001 seconds There are 184756 paths in a 10 sized grid 0,001 seconds There are 705432 paths in a 11 sized grid 0 seconds There are 2704156 paths in a 12 sized grid 0 seconds There are 10400600 paths in a 13 sized grid 0,001 seconds There are 40116600 paths in a 14 sized grid 0 seconds There are 155117520 paths in a 15 sized grid 0 seconds There are 601080390 paths in a 16 sized grid 0,0010001 seconds There are 2333606220 paths in a 17 sized grid 0,001 seconds There are 9075135300 paths in a 18 sized grid 0,001 seconds There are 35345263800 paths in a 19 sized grid 0,001 seconds There are 137846528820 paths in a 20 sized grid 0,0010001 seconds 0,0390022 seconds in total I'm accepting danben's answer, because his helped me find this solution the most. But upvotes also to Tim Goodman and Agos :) Bonus update: After reading Eric Lippert's answer, I took another look and rewrote it somewhat. The basic idea is still the same but the caching part has been taken out and put in a separate function, like in Eric's example. The result is some much more elegant looking code. // the size of our grid const int gridSize = 20; // magic. static Func<A1, A2, R> Memoize<A1, A2, R>(this Func<A1, A2, R> f) { // Return a function which is f with caching. var dictionary = new Dictionary<string, R>(); return (A1 a1, A2 a2) => { R r; string key = a1 + "x" + a2; if (!dictionary.TryGetValue(key, out r)) { // not in cache yet r = f(a1, a2); dictionary.Add(key, r); } return r; }; } // calculate the surface of the block to the finish line static long calcsurface(long x, long y) { return (gridSize - x) * (gridSize - y); } // call using progress (0, 0) static Func<long, long, long> progress = ((Func<long, long, long>)((long x, long y) => { // first calculate the surface of the block remaining long surface = calcsurface(x, y); long i = 0; // zero surface means only 1 path remains // (we either go only right, or only down) if (surface == 0) return 1; // calculate it in the right direction if (x < gridSize) i += progress(x + 1, y); // and in the down direction if (y < gridSize) i += progress(x, y + 1); // self-explanatory :) return i; })).Memoize(); By the way, I couldn't think of a better way to use the two arguments as a key for the dictionary. I googled around a bit, and it seems this is a common solution. Oh well.

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