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• Loading a RSA private key from memory using libxmlsec

  - by ereOn

  Hello, I'm currently using libxmlsec into my C++ software and I try to load a RSA private key from memory. To do this, I searched trough the API and found this function. It takes binary data, a size, a format string and several PEM-callback related parameters. When I call the function, it just stucks, uses 100% of the CPU time and never returns. Quite annoying, because I have no way of finding out what is wrong. Here is my code: d_xmlsec_dsig_context->signKey = xmlSecCryptoAppKeyLoadMemory( reinterpret_cast<const xmlSecByte*>(data), static_cast<xmlSecSize>(datalen), xmlSecKeyDataFormatBinary, NULL, NULL, NULL ); data is a const char* pointing to the raw bytes of my RSA key (using i2d_RSAPrivateKey(), from OpenSSL) and datalen the size of data. My test private key doesn't have a passphrase so I decided not to use the callbacks for the time being. Has someone already done something similar ? Do you guys see anything that I could change/test to get forward on this problem ? I just discovered the library on yesterday, so I might miss something obvious here; I just can't see it. Thank you very much for your help.

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• Is there a GUI that I can use to create XML documents based on my schema?

  - by David Conlisk

  Hi all, I want to create a simple graphical user interface to allow non-technical users to create an XML file without having to manually edit the XML source. Ideally I'd like a drag and drop interface, but failing that, anything really. The contents of the XML file are similar to an encoded flow chart of a binary tree, so maybe something like Visio, with a save as xml option? Here's a quick sample of the XML output that is required: <?xml version="1.0" encoding="utf-8"?> <steps> <step id="1" type="prompt"> <prompt> Welcome. </prompt> <next>1.1</next> </step> <step id="1.1" type="question"> <prompt> Do you have what you need? </prompt> <yes>1.2</yes> <no>1.1.1</no> </step> ... </steps> Are there any existing tools out there that you can recommend for this purpose? Ideally open-source or with a free personal license, but I'm interested in hearing about all options. Thanks, David

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• Is this a good approach to address double-base64-encoding?

  - by Freiheit

  My software understands attachments, like PNGs attached to user records. These attachments are usually sent in from outside sources as a Base64 encoded string. The database stores whatever data it is given, Base64 encoded or not. When I serve up the attachment for download I do this: if (Base64.isBase64(data)) { data = Base64.decodeBase64(data); } There is a potential for data that is double encoded. For instance the sender of a message had base64 encoded data, then encoded it again when building the message to send to me. I think the following code would address that circumstance: while (Base64.isBase64(data)) { data = Base64.decodeBase64(data); } So if data is encoded multiple times, it would be decoded until its in its 'raw' state and then served up for download. Is this approach an acceptable way to address that problem? Ideally some sort of checking could happen at the edge when I receive attachment data, but that will take more time. This looping seems to be a faster way to do it. The 'Base64' library is Apache Commons: http://commons.apache.org/codec/apidocs/org/apache/commons/codec/binary/Base64.html I trust it to properly identify Base64 encoded data.

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• Why does perl crash with "*** glibc detected *** perl: munmap_chunk(): invalid pointer"?

  - by sid_com

  #!/usr/bin/env perl use warnings; use strict; use 5.012; use XML::LibXML::Reader; my $reader = XML::LibXML::Reader->new( location => 'http://www.heise.de/' ) or die $!; while ( $reader->read ) { say $reader->name; } At the end of the output from this script I get this error-messages: * glibc detected * perl: munmap_chunk(): invalid pointer: 0x0000000000b362e0 * ======= Backtrace: ========= /lib64/libc.so.6[0x7fb84952fc76] ... ======= Memory map: ======== 00400000-0053d000 r-xp 00000000 08:01 182002 /usr/local/bin/perl ... Is this due a bug? perl -V: Summary of my perl5 (revision 5 version 12 subversion 0) configuration: Platform: osname=linux, osvers=2.6.31.12-0.2-desktop, archname=x86_64-linux uname='linux linux1 2.6.31.12-0.2-desktop #1 smp preempt 2010-03-16 21:25:39 +0100 x86_64 x86_64 x86_64 gnulinux ' config_args='-Dnoextensions=ODBM_File' hint=recommended, useposix=true, d_sigaction=define useithreads=undef, usemultiplicity=undef useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef use64bitint=define, use64bitall=define, uselongdouble=undef usemymalloc=n, bincompat5005=undef Compiler: cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64', optimize='-O2', cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include' ccversion='', gccversion='4.4.1 [gcc-4_4-branch revision 150839]', gccosandvers='' intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678 d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16 ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8 alignbytes=8, prototype=define Linker and Libraries: ld='cc', ldflags =' -fstack-protector -L/usr/local/lib' libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64 /usr/local/lib64 libs=-lnsl -ldl -lm -lcrypt -lutil -lc perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc libc=/lib/libc-2.10.1.so, so=so, useshrplib=false, libperl=libperl.a gnulibc_version='2.10.1' Dynamic Linking: dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E' cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector' Characteristics of this binary (from libperl): Compile-time options: PERL_DONT_CREATE_GVSV PERL_MALLOC_WRAP USE_64_BIT_ALL USE_64_BIT_INT USE_LARGE_FILES USE_PERLIO USE_PERL_ATOF Built under linux Compiled at Apr 15 2010 13:25:46 @INC: /usr/local/lib/perl5/site_perl/5.12.0/x86_64-linux /usr/local/lib/perl5/site_perl/5.12.0 /usr/local/lib/perl5/5.12.0/x86_64-linux /usr/local/lib/perl5/5.12.0 .

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• Integrating twitpic OAuth for iPhone.

  - by asadqamber

  How can I integrate twitpic API with OAuth for posting an image from iPhone? Any help or tutorial? Currently I am doing... NSURL *twitpicURL = [NSURL URLWithString:@"http://api.twitpic.com/2/upload.format"]; theRequest = [NSMutableURLRequest requestWithURL:twitpicURL]; [theRequest setHTTPMethod:@"POST"]; // Set the params NSString *message = theMessage; [theRequest addValue:@"http://api.twitter.com/" forHTTPHeaderField:@"OAuth realm"]; [theRequest addValue:TWITPIC_API_KEY forHTTPHeaderField:@"oauth_consumer_key"]; [theRequest addValue:@"HMAC-SHA1" forHTTPHeaderField:@"oauth_signature_method"]; [theRequest addValue:USER_OAUTH_TOKEN forHTTPHeaderField:@"oauth_token"]; [theRequest addValue:USER_OAUTH_SECRET forHTTPHeaderField:@"oauth_secret"]; [theRequest addValue: @"1272325550" forHTTPHeaderField:@"oauth_timestamp"]; [theRequest addValue:nil forHTTPHeaderField:@"oauth_nonce"]; [theRequest addValue:@"1.0" forHTTPHeaderField:@"oauth_version"]; [theRequest addValue:nil forHTTPHeaderField:@"oauth_signature"]; NSMutableData *postBody = [NSMutableData data]; [postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"source\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithFormat:@"lighttable"] dataUsingEncoding:NSUTF8StringEncoding]]; // Message [postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"message\"\r\n\r\n%@", message]dataUsingEncoding:NSUTF8StringEncoding]]; // Media [postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"media\"; filename=\"%@\"\r\n", @"doc_twitpic_image.jpg"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[[NSString stringWithFormat:@"Content-Type: image/jpg\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; // data as JPEG [postBody appendData:[[NSString stringWithFormat:@"Content-Transfer-Encoding: binary\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; [postBody appendData:[NSData dataWithData:image]]; [theRequest setHTTPBody:postBody]; [theRequest setValue:[NSString stringWithFormat:@"%d", [postBody length]] forHTTPHeaderField:@"Content-Length"]; theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

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• Symfony/Propel NestedSet left/right ID corruption/adjustment

  - by Mike Crowe

  Hi folks, I have a nested set application that seems to be getting corrupted. Here's what I'm seeing: We're using nested sets for a binary tree (any node can have 2 children). It appears to be working fine, but some event causes a discrepancy. For instance, when I do a getNumberOfDescendants() for the root node, it will slowly increase as this event happens. However, displaying the tree works fine, as does inserting (apparently). Has anybody seen anything like this before? For instance, my repair program shows this as the repairs that it makes: User pxxxxx left 0=>0, right 145=>129 User axxxxx left 1=>1, right 124=>106 User mxxxxx left 119=>117, right 120=>118 User fxxxxx left 125=>107, right 144=>128 User fxxxxx left 126=>108, right 131=>113 User rxxxxx left 127=>109, right 128=>110 User mxxxxx left 129=>111, right 130=>112 User mxxxxx left 132=>114, right 143=>127 User cxxxxx left 133=>115, right 142=>126 User gxxxxx left 134=>116, right 137=>121 User mxxxxx left 135=>119, right 136=>120 User jxxxxx left 138=>122, right 141=>125 User axxxxx left 139=>123, right 140=>124 I thought at first it was when I deleted a user, but it has since occurred w/o that event. Anybody know of a cause that might generate this? I've tested ad nauseum on my local machine, but I can't duplicate it. I do have an issue where my production box is PHP 5.2.0, whereas my test device is 5.2.10. Could that be an issue? TIA Mike

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• Average of two strings in alphabetical order

  - by Bemmu

  Suppose you take the strings 'a' and 'z' and list all the strings that come between them in alphabetical order: ['a','b','c' ... 'x','y','z']. Take the midpoint of this list and you find 'm'. So this is kind of like taking an average of those two strings. You could extend it to strings with more than one character, for example the midpoint between 'aa' and 'zz' would be found in the middle of the list ['aa', 'ab', 'ac' ... 'zx', 'zy', 'zz']. Might there be a Python method somewhere that does this? If not, even knowing the name of the algorithm would help. I began making my own routine that simply goes through both strings and finds midpoint of the first differing letter, which seemed to work great in that 'aa' and 'az' midpoint was 'am', but then it fails on 'cat', 'doggie' midpoint which it thinks is 'c'. Rather than invent a method I thought it better to ask. I tried Googling for "binary search string midpoint" etc. but without knowing the name of what I am trying to do here I had little luck.

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• Trying to use a authlogic-connect as a plugin in place of gem - Server doesn't start

  - by Arkid

  I am trying to use Authlogic-connect as a plugin in Rails 3 in place of a gem. I have made an entry in the gemfile as gem "authlogic-connect", :require => "authlogic-connect", :path => "localgems" Now when I run the bundle install, it runs fine. When I try to start the server i get the error Could not find gem 'authlogic-connect (>= 0, runtime)' in source at localgems. Source does not contain any versions of 'authlogic-connect (>= 0, runtime)' Try running `bundle install`. I have placed the unzipped Gem renamed as authlogic-connect in the localgems folder. what is the problem? Here is what I get on using rails plugin install arkidmitra$ rails plugin install git://github.com/viatropos/authlogic-connect.git Usage: rails new APP_PATH [options] Options: [--skip-gemfile] # Don't create a Gemfile -d, [--database=DATABASE] # Preconfigure for selected database (options: mysql/oracle/postgresql/sqlite3/frontbase/ibm_db) # Default: sqlite3 -O, [--skip-active-record] # Skip Active Record files [--dev] # Setup the application with Gemfile pointing to your Rails checkout -J, [--skip-prototype] # Skip Prototype files -T, [--skip-test-unit] # Skip Test::Unit files -G, [--skip-git] # Skip Git ignores and keeps -r, [--ruby=PATH] # Path to the Ruby binary of your choice # Default: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby -m, [--template=TEMPLATE] # Path to an application template (can be a filesystem path or URL) -b, [--builder=BUILDER] # Path to an application builder (can be a filesystem path or URL) [--edge] # Setup the application with Gemfile pointing to Rails repository Runtime options: -q, [--quiet] # Supress status output -s, [--skip] # Skip files that already exist -f, [--force] # Overwrite files that already exist -p, [--pretend] # Run but do not make any changes Rails options: -h, [--help] # Show this help message and quit -v, [--version] # Show Rails version number and quit Description: The 'rails new' command creates a new Rails application with a default directory structure and configuration at the path you specify. Example: rails new ~/Code/Ruby/weblog This generates a skeletal Rails installation in ~/Code/Ruby/weblog. See the README in the newly created application to get going.

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• Understanding floating point problems

  - by Maxim Gershkovich

  Could someone here please help me understand how to determine when floating point limitations will cause errors in your calculations. For example the following code. CalculateTotalTax = function (TaxRate, TaxFreePrice) { return ((parseFloat(TaxFreePrice) / 100) * parseFloat(TaxRate)).toFixed(4); }; I have been unable to input any two values that have caused for me an incorrect result for this method. If I remove the toFixed(4) I can infact see where the calculations start to lose accuracy (somewhere around the 6th decimal place). Having said that though, my understanding of floats is that even small numbers can sometimes fail to be represented or have I misunderstood and can 4 decimal places (for example) always be represented accurately. MSDN explains floats as such... This means they cannot hold an exact representation of any quantity that is not a binary fraction (of the form k / (2 ^ n) where k and n are integers) Now I assume this applies to all floats (inlcuding those used in javascript). Fundamentally my question boils down to this. How can one determine if any specific method will be vulnerable to errors in floating point operations, at what precision will those errors materialize and what inputs will be required to produce those errors? Hopefully what I am asking makes sense.

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• ai: Determining what tests to run to get most useful data

  - by Sai Emrys

  This is for http://cssfingerprint.com I have a system (see about page on site for details) where: I need to output a ranked list, with confidences, of categories that match a particular feature vector the binary feature vectors are a list of site IDs & whether this session detected a hit feature vectors are, for a given categorization, somewhat noisy (sites will decay out of history, and people will visit sites they don't normally visit) categories are a large, non-closed set (user IDs) my total feature space is approximately 50 million items (URLs) for any given test, I can only query approx. 0.2% of that space I can only make the decision of what to query, based on results so far, ~10-30 times, and must do so in <~100ms (though I can take much longer to do post-processing, relevant aggregation, etc) getting the AI's probability ranking of categories based on results so far is mildly expensive; ideally the decision will depend mostly on a few cheap sql queries I have training data that can say authoritatively that any two feature vectors are the same category but not that they are different (people sometimes forget their codes and use new ones, thereby making a new user id) I need an algorithm to determine what features (sites) are most likely to have a high ROI to query (i.e. to better discriminate between plausible-so-far categories [users], and to increase certainty that it's any given one). This needs to take into balance exploitation (test based on prior test data) and exploration (test stuff that's not been tested enough to find out how it performs). There's another question that deals with a priori ranking; this one is specifically about a posteriori ranking based on results gathered so far. Right now, I have little enough data that I can just always test everything that anyone else has ever gotten a hit for, but eventually that won't be the case, at which point this problem will need to be solved. I imagine that this is a fairly standard problem in AI - having a cheap heuristic for what expensive queries to make - but it wasn't covered in my AI class, so I don't actually know whether there's a standard answer. So, relevant reading that's not too math-heavy would be helpful, as well as suggestions for particular algorithms. What's a good way to approach this problem?

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• mysql match against russain

  - by Devenv

  Hey, Trying to solve this for a very long time now... SELECT MATCH(name) AGAINST('????????') (russian) doesn't work, but SELECT MATCH(name) AGAINST('abraxas') (english) work perfectly. I know it's something with character-set, but I tried all kind of settings and it didn't work. For now it's latin-1. LIKE works This is the show variables charset related: character_set_client - latin1 character_set_connection - latin1 character_set_database - latin1 character_set_filesystem - binary character_set_results - latin1 character_set_server - latin1 character_set_system - utf8 character_sets_dir - /usr/share/mysql/charsets/ collation_connection - latin1_swedish_ci collation_database - latin1_swedish_ci collation_server - latin1_swedish_ci chunk of /etc/my.cnf default-character-set=latin1 skip-character-set-client-handshake chunk of the dump: /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */; /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */; /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */; /*!40101 SET NAMES utf8 */; DROP TABLE IF EXISTS `scenes_raw`; /*!40101 SET @saved_cs_client = @@character_set_client */; /*!40101 SET character_set_client = utf8 */; CREATE TABLE `scenes_raw` ( `scene_name` varchar(40) DEFAULT NULL, ...blabla... ) ENGINE=MyISAM AUTO_INCREMENT=901 DEFAULT CHARSET=utf8; (I did tests without skip-character-set-client-handshake too) SHOW TABLE STATUS WHERE Name = 'scenes_raw'\G Name: scenes_raw Engine: MyISAM Version: 10 Row_format: Dynamic Index_length: 23552 Collation: utf8_general_ci Checksum: NULL Create_options:

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• Exporting static data in a DLL

  - by Gayan

  I have a DLL which contains a class with static members. I use __declspec(dllexport) in order to make use of this class's methods. But when I link it to another project and try to compile it, I get "unresolved external symbol" errors for the static data. e.g. In DLL, Test.h class __declspec(dllexport) Test{ protected: static int d; public: static void m(){} } In DLL, Test.cpp #include "Test.h" int Test::d; In the application which uses Test, I call m(). I also tried using __declspec(dllexport) for each method separately but I still get the same link errors for the static members. If I check the DLL (the .lib) using dumpbin, I could see that the symbols have been exported. For instance, the app gives the following error at link time: 1>Main.obj : error LNK2001: unresolved external symbol "protected: static int CalcEngine::i_MatrixRow" (?i_MatrixRow@CalcEngine@@1HA) But the dumpbin of the .lib contains: Version : 0 Machine : 14C (x86) TimeDateStamp: 4BA3611A Fri Mar 19 17:03:46 2010 SizeOfData : 0000002C DLL name : CalcEngine.dll Symbol name : ?i_MatrixRow@CalcEngine@@1HA (protected: static int CalcEngine::i_MatrixRow) Type : data Name type : name Hint : 31 Name : ?i_MatrixRow@CalcEngine@@1HA I can't figure out how to solve this. What am I doing wrong? How can I get over these errors? P.S. The code was originally developed for Linux and the .so/binary combination works without a problem

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• Difficulties using custom control - RichTextEditor

  - by Chris

  I am working on a school project that uses ASP.NET. I found this TextEditor control ( http://blogs.msdn.com/kirti/archive/2007/11/10/rich-text-editor-is-here.aspx ) that I am trying to include but it isn't working. The error I am getting is: Error Rendering Control - TextEditor. An unhandled exception has occurred. Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index. I see this error when I go Design part of the editor. I just don't understand this error at all. Also I am a lil bit confused as there is no parameter called index. :( What I have done is reference the binary in my project and then on the page I am trying to use it have registered its namespace and assembly with this line: <%@ Register Assembly="RichTextEditor" Namespace="AjaxControls" TagPrefix="rtt" %> I then go ahead and try to add the control to the page with this line of code: <rtt:richtexteditor ID="TextEditor" Theme="Blue" runat="server" /> Any help would be much appreciated. I haven't done anything like add a custom control before.

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• reconstructing a tree from its preorder and postorder lists.

  - by NomeN

  Consider the situation where you have two lists of nodes of which all you know is that one is a representation of a preorder traversal of some tree and the other a representation of a postorder traversal of the same tree. I believe it is possible to reconstruct the tree exactly from these two lists, and I think I have an algorithm to do it, but have not proven it. As this will be a part of a masters project I need to be absolutely certain that it is possible and correct (Mathematically proven). However it will not be the focus of the project, so I was wondering if there is a source out there (i.e. paper or book) I could quote for the proof. (Maybe in TAOCP? anybody know the section possibly?) In short, I need a proven algorithm in a quotable resource that reconstructs a tree from its pre and post order traversals. Note: The tree in question will probably not be binary, or balanced, or anything that would make it too easy. Note2: Using only the preorder or the postorder list would be even better, but I do not think it is possible. Note3: A node can have any amount of children. Note4: I only care about the order of siblings. Left or right does not matter when there is only one child.

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• How do I build BugTrap?

  - by magnifico

  I am trying to build the Itellesoft BugTrap source using Visual Studio 2008. I have downloaded and unziped the BugTrap source and the zlib source. I navigated down to ./BugTrap/Win32/BugTrap and opened BugTrap.sln (suggest by the author here). I used Build-Build Solution and the build failed with a compiler error: fatal error C1083: Cannot open include file: 'zip.h': No such file or directory I opened the project properties and added the path to the zlib-vc/zlib/include folder to the list of "Additional Include Directories" and tried to build again. The second build attempt failed with a linker error: fatal error LNK1104: cannot open file 'zlibSD.lib' I opened the zlib project and built the source. The zlib build succeeded. However, the bin directory does not contain a zlibSD.lib. The closest file in name is zlibMSD.lib. This poster on CodeProject seemed to have the same problem I did. But there is no resolution posted. Hopefully someone out there has experience building this project and can point me in the right direction, I've played with the binary distribution and it seems really slick.

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• How to sort a list so that managers are always ahead of their subordinates

  - by James Black

  I am working on a project using Groovy, and I would like to take an array of employees, so that no manager follows their subordinates in the array. The reason being that I need to add people to a database and I would prefer not to do it in two passes. So, I basically have: <employees> <employee> <employeeid>12</employeeid> <manager>3</manager> </employee> <employee> <employeeid>1</employeeid> <manager></manager> </employee> <employee> <employeeid>3</employeeid> <manager>1</manager> </employee> </employees> So, it should be sorted as such: employeeid = 1 employeeid = 3 employeeid = 12 The first person should have a null for managers. I am thinking about a binary tree representation, but I expect it will be very unbalanced, and I am not certain the best way to do this using Groovy properly. Is there a way to do this that isn't going to involve using nested loops?

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• Detecting Asymptotes in a Graph

  - by nasufara

  I am creating a graphing calculator in Java as a project for my programming class. There are two main components to this calculator: the graph itself, which draws the line(s), and the equation evaluator, which takes in an equation as a String and... well, evaluates it. To create the line, I create a Path2D.Double instance, and loop through the points on the line. To do this, I calculate as many points as the graph is wide (e.g. if the graph itself is 500px wide, I calculate 500 points), and then scale it to the window of the graph. Now, this works perfectly for most any line. However, it does not when dealing with asymptotes. If, when calculating points, the graph encounters a domain error (such as 1/0), the graph closes the shape in the Path2D.Double instance and starts a new line, so that the line looks mathematically correct. Example: However, because of the way it scales, sometimes it is rendered correctly, sometimes it isn't. When it isn't, the actual asymptotic line is shown, because within those 500 points, it skipped over x = 2.0 in the equation 1 / (x-2), and only did x = 1.98 and x = 2.04, which are perfectly valid in that equation. Example: In that case, I increased the window on the left and right one unit each. My question is: Is there a way to deal with asymptotes using this method of scaling so that the resulting line looks mathematically correct? I myself have thought of implementing a binary search-esque method, where, if it finds that it calculates one point, and then the next point is wildly far away from the last point, it searches in between those points for a domain error. I had trouble figuring out how to make it work in practice, however. Thank you for any help you may give!

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• haskell: a data structure for storing ascending integers with a very fast lookup

  - by valya

  Hello! (This question is related to my previous question, or rather to my answer to it.) I want to store all qubes of natural numbers in a structure and look up specific integers to see if they are perfect cubes. For example, cubes = map (\x -> x*x*x) [1..] is_cube n = n == (head $ dropWhile (<n) cubes) It is much faster than calculating the cube root, but It has complexity of O(n^(1/3)) (am I right?). I think, using a more complex data structure would be better. For example, in C I could store a length of an already generated array (not list - for faster indexing) and do a binary search. It would be O(log n) with lower ?oefficient than in another answer to that question. The problem is, I can't express it in Haskell (and I don't think I should). Or I can use a hash function (like mod). But I think it would be much more memory consuming to have several lists (or a list of lists), and it won't lower the complexity of lookup (still O(n^(1/3))), only a coefficient. I thought about a kind of a tree, but without any clever ideas (sadly I've never studied CS). I think, the fact that all integers are ascending will make my tree ill-balanced for lookups. And I'm pretty sure this fact about ascending integers can be a great advantage for lookups, but I don't know how to use it properly (see my first solution which I can't express in Haskell).

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• Producing CCITT compressed TIFF from CGImage

  - by Brian Postow

  I have a CGImage (core graphics, C/C++). It's grayscale. Well, originally it was B/W, but the CGImage may be RGB. That shouldn't matter. I want to create a CCITT-Group 4 TIFF. I can create an LZW TIFF (grayscale or color) via creating a destination with the correct dictionary and adding the image in. No problem. However, there doesn't seem to be an equivalent kCGImagePropertyTIFFCompression value to represent CCITT-4. It should be 4, but that produces uncompressed. I have a manual CCITT compression routine, so if I can get the binary (1 bit per pixel) data, I'm set. But I can't seem to get 1 BPP data out of a CGImage. I have code that is supposed to put the CGImage into a CGBitmapContext and then give me the data, but it seems to be giving me all black. I've asked a couple of questions today trying to get at this, but I just figured, lets ask the question I REALLY want answered and see if someone can answer it. There's GOT to be a way to do this. I've got to be missing something dumb. What is it?

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• Retrieve Flash file post in ASP.NET

  - by Quandary

  Question: In ASP.NET, I retrieve a JPEG-file as Flash post data like this Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest context.Response.ContentType = "text/plain" ' Retrieve a bytearray from the post buffer Dim myBuffer As Byte() = context.Request.BinaryRead(Convert.ToInt32(context.Request.InputStream.Length)) System.IO.File.WriteAllBytes("c:\temp\test.jpg", myBuffer) End Sub In Flash, I send it to an asp.net handler like this var jpgSource:BitmapData = cPrint.TakeSnapshot(MovieClip(cGlobals.ccPlanZoomView)); var bmpThisBitmap:Bitmap = new Bitmap(jpgSource); var nQuality:Number = 100; var jpgEncoder:JPGEncoder = new JPGEncoder(nQuality); var jpgStream:ByteArray = jpgEncoder.encode(jpgSource); var header:URLRequestHeader = new URLRequestHeader ("Content-type", "application/octet-stream"); // Make sure to use the correct path to jpg_encoder_download.php var strFileName:String="test.jpg"; var jpgURLRequest:URLRequest = new URLRequest("http://localhost/raumplaner_new/raumplaner_new/cgi-bin/SavePDF.ashx"); //var scriptVars:URLVariables = new URLVariables(); //scriptVars.fn = strFileName; //var myarr:Array= new Array(); //myarr.push(jpgStream); //scriptVars.Files = myarr; jpgURLRequest.requestHeaders.push(header); jpgURLRequest.method = URLRequestMethod.POST; //jpgURLRequest.data = scriptVars; jpgURLRequest.data = jpgStream; var loader:URLLoader = new URLLoader(); loader.dataFormat = URLLoaderDataFormat.BINARY; loader.load(jpgURLRequest); It works but I want to send a few additional variables along, via scriptVars (commented out here). How do I retrieve the JPEG file in that case ? Because if I use parameters, there is no more BinaryRead... Aspecially, how would I read an array of jpeg files (several files) ?

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• Shared value in parallel python

  - by Jonathan

  Hey all- I'm using ParallelPython to develop a performance-critical script. I'd like to share one value between the 8 processes running on the system. Please excuse the trivial example but this illustrates my question. def findMin(listOfElements): for el in listOfElements: if el < min: min = el import pp min = 0 myList = range(100000) job_server = pp.Server() f1 = job_server.submit(findMin, myList[0:25000]) f2 = job_server.submit(findMin, myList[25000:50000]) f3 = job_server.submit(findMin, myList[50000:75000]) f4 = job_server.submit(findMin, myList[75000:100000]) The pp docs don't seem to describe a way to share data across processes. Is it possible? If so, is there a standard locking mechanism (like in the threading module) to confirm that only one update is done at a time? l = Lock() if(el < min): l.acquire if(el < min): min = el l.release I understand I could keep a local min and compare the 4 in the main thread once returned, but by sharing the value I can do some better pruning of my BFS binary tree and potentially save a lot of loop iterations. Thanks- Jonathan

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• [ASP.NET] Difficulties using custom control - RichTextEditor

  - by Chris

  I am working on a school project that uses ASP.NET. I found this TextEditor control ( http://blogs.msdn.com/kirti/archive/2007/11/10/rich-text-editor-is-here.aspx ) that I am trying to include but it isn't working. The error I am getting is: Error Rendering Control - TextEditor. An unhandled exception has occurred. Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index. I see this error when I go Design part of the editor. I just don't understand this error at all. Also I am a lil bit confused as there is no parameter called index. :( What I have done is reference the binary in my project and then on the page I am trying to use it have registered its namespace and assembly with this line: <%@ Register Assembly="RichTextEditor" Namespace="AjaxControls" TagPrefix="rtt" %> I then go ahead and try to add the control to the page with this line of code: <rtt:richtexteditor ID="TextEditor" Theme="Blue" runat="server" /> Any help would be much appreciated. I haven't done anything like add a custom control before.

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• CURL & web.py: transfer closed with outstanding read data remaining

  - by Richard J

  Hi Folks, I have written a web.py POST handler, thus: import web urls = ('/my', 'Test') class Test: def POST(self): return "Here is your content" app = web.application(urls, globals()) if __name__ == "__main__": app.run() When I interact with it using Curl from the command line I get different responses depending on whether I post it any data or not: curl -i -X POST http://localhost:8080/my HTTP/1.1 200 OK Transfer-Encoding: chunked Date: Thu, 06 Jan 2011 16:42:41 GMT Server: CherryPy/3.1.2 WSGI Server Here is your content (Posting of no data to the server gives me back the "Here is your content" string) curl -i -X POST --data-binary "@example.zip" http://localhost:8080/my HTTP/1.1 100 Content-Length: 0 Content-Type: text/plain HTTP/1.1 200 OK Transfer-Encoding: chunked Date: Thu, 06 Jan 2011 16:43:47 GMT Server: CherryPy/3.1.2 WSGI Server curl: (18) transfer closed with outstanding read data remaining (Posting example.zip to the server results in this error) I've scoured the web.py documentation (what there is of it), and can't find any hints as to what might be going on here. Possibly something to do with 100 continue? I tried writing a python client which might help clarify: h1 = httplib.HTTPConnection('localhost:8080') h1.request("POST", "http://localhost:8080/my", body, headers) print h1.getresponse() body = the contents of the example.zip, and headers = empty dictionary. This request eventually timed out without printing anything, which I think exonerates curl from being the issue, so I believe something is going on in web.py which isn't quite right (or at least not sufficiently clear) Any web.py experts got some tips? Cheers, Richard

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• Finding text orientation in image (angle for rotation)

  - by maximus

  There is an image captured by camera, and I need to find the angle of the text in order to rotate it to make the image better for OCR results. So I know that the fourier transform can be used for that purpose, My question is, does it really gives good results or may be it is better to use something different than that? Can you tell me if there is a good method for this purpose? I am afraid that not every image containing the text will give me a good result after using fourier transform method. Actually, if I make like it is written here: link text (see the part related with an example of text image) calculating the logarithm of the magnitude of the Fourier transform of image with text and then thresholding it, I get that points and I can calculate the line approximately passing through them, and after getting the line calculate the angle, and then make an affine transform, But, what if I do not get a good result every time using this method , and make a false transform? Any ideas please to judge wether the result is correct or not, or may be another method is better? The binary image can contain noise, even if there are not so much of them, the angle found as a result can be not accurate.

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• Download MMS content on Blackberry

  - by Chris

  Hi I am relatively new to coding for the blackberry and I need to write a java application that can capture all incoming and outgoing MMS data from a Blackberry device. I have gotten the capturing of outgoing MMS's sorted with the use of A sendListener, but the problem comes with the incoming MMS's. If I use a MessageListener that processes only those of type BinaryMessage, i can capture the binary notification SMS that comes in when there is an incoming MMS. From this notification, i can get the senders MSISDN as well as the URL on the MMSC where the content is stored. To get the actual MMS content, i presume i need to download it from this URL, but im unable to get this working. I have tried just opening a HTTPConnetion to this URL, opening an inputStream on it and reading from there, but i retrieve no content. If i manually go to that URL on the blackberry, i can see the content fine (and of course the blackberry can download it automatically anyway). Can anyone please help me asap on how i can get the mms content for incoming MMS's. Thanks alot

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