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Search found 1933 results on 78 pages for 'genetic algorithms'.

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• What's the most straightforward way to typeset MLA-style college essays in LaTeX?

  - by bcat

  I've been using LaTeX for a little while now to typeset my algorithms homework, and I really like the quality of the output as well as the ease-of-use. I'd like to starting using LaTeX in other classes as well, but non–computer-science subjects have more stringent formatting requirements than I've come across in CS. Most classes that require essays want them to be formatted in MLA style, but I'm not sure what to best way to do that using LaTeX is. I've tried Googling "latex mla" and other similar things, but I've found many different MLA templates, and my LaTeX skills aren't good enough to determine which is the best. Is anyone else using LaTeX for "normal" essays, and, if so, how are you doing it?

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• Do similar passwords have similar hashes?

  - by SLC

  Our computer system at work requires users to change their password every few weeks, and you cannot have the same password as you had previously. It remembers something like 20 of your last passwords. I discovered most people simply increment a digit at the end of their password, so "thisismypassword1" becomes "thisismypassword2" then 3, 4, 5 etc. Since all of these passwords are stored somewhere, I wondered if there was any weakness in the hashes themselves, for standard hashing algorithms used to store passwords like MD5. Could a hacker increase their chances of brute-forcing the password if they have a list of hashes of similar passwords?

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• How to double the size of 8x8 Grid whilst keeping the relative position of certain tiles intact?

  - by ke3pup

  Hi guys I have grid size of size 8x8 , total of 64 Tiles. i'm using this Grid to implement java search algorithms such as BFS and DFS. The Grid has given forbidden Tiles (meaning they can't be traversed or be neighbour of any other tile) and Goal and Start tile. for example Tile 19,20,21,22 and 35, 39 are forbidden and 14 an 43 are the Goal and start node when the program runs. My question is , How can i double the size of the grid, to 16x16 whilst keeping the Relative position of forbidden tiles as well as the Relative position of start and goal Tiles intact? On paper i know i can do this by adding 4 rows and columns to all size but in coding terms i don't know how to make it work? Can someone please give any sort of hints?

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• "Did you mean" feature on a dictionary database

  - by Hazar

  I have a ~300.000 row table; which includes technical terms; queried using PHP and MySQL + FULLTEXT indexes. But when I searching a wrong typed term; for example "hyperpext"; naturally giving no results. I need to "compansate" little writing errors and getting nearest record from database. How I can accomplish such feaure? I know (actually, learned today) about Levenshtein distance, Soundex and Metaphone algorithms but currently not having a solid idea to implement this to querying against database. Best regards. (Sorry about my poor English, I'm trying to do my best)

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• CSV parser in C++

  - by User1

  All I need is a good CSV file parser for C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called. I found this article which looks quite promising: http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp I've never used Boost's Spirit, but am willing to try it. Is it overkill/bloated or is it fast and efficient? Does anyone have faster algorithms using STL or anything else? Thanks!

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• The easiest way to draw an image?

  - by Benno

  Assume you want to read an image file in a common file format from the hard drive, change the color of one pixel, and display the resulting image to the screen, in C++. Which (open-source) libraries would you recommend to accomplish the above with the least amount of code? Alternatively, which libraries would do the above in the most elegant way possible? A bit of background: I have been reading a lot of computer graphics literature recently, and there are lots of relatively easy, pixel-based algorithms which I'd like to implement. However, while the algorithm itself would usually be straightforward to implement, the necessary amount of frame-work to manipulate an image on a per-pixel basis and display the result stopped me from doing it.

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• Two parallel line segments intersection

  - by Judarkness

  I know there are many algorithms to verify whether two line segments are intersected. But once they encountered parallel condition, they just tell the user a big "No" and pretend there is no overlap, share end point, or end point collusion. I know I can can calculate the distance between 2 lines segments. If the distance is 0, check the end points located in the other line segments or not. And this means I have to use a lot of if else and && || conditions. This is not difficult, but my question is "Is there a trick( or mathematics) method to calculate this special parallel case?"

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• Have you ever derived a programming solution from nature?

  - by Ryu

  When you step back and look at ... the nature of animals, insects, plants and the problems they have organically solved perhaps even the nature and balance of the universe Have you ever been able to solve a problem by deriving an approach from nature? I've heard of Ant Colony Algorithms being able to optimize supply chain amongst other things. Also Fractal's being the "geometry of nature" have been applied to a wide range of problems. Now that spring is here again and the world is coming back to life I'm wondering if anybody has some experiences they can share. Thanks PS I would recommend watching the "Hunting the Hidden Dimension" Nova episode on fractals.

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• Subdividing 3D mesh into arbitrarily sized pieces

  - by Groky

  I have a mesh defined by 4 points in 3D space. I need an algorithm which will subdivide that mesh into subdivisions of an arbitrary horizontal and vertical size. If the subdivision size isn't an exact divisor of the mesh size, the edge pieces will be smaller. All of the subdivision algorithms I've found only subdivide meshes into exact powers of 2. Does anyone know of one that can do what I want? Failing that, my thoughts about a possible implementation is to rotate the mesh so that it is flat on the Z axis, subdivide in 2D and then translate back into 3D. That's because my mind finds 3D hard ;) Any better suggestions? Using C# if that makes any difference.

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• Secure password transmission over unencrypted tcp/ip

  - by academicRobot

  I'm in the designing stages of a custom tcp/ip protocol for mobile client-server communication. When not required (data is not sensitive), I'd like to avoid using SSL for overhead reasons (both in handshake latency and conserving cycles). My question is, what is the best practices way of transmitting authentication information over an unencrypted connection? Currently, I'm liking SRP or J-PAKE (they generate secure session tokens, are hash/salt friendly, and allow kicking into TLS when necessary), which I believe are both implemented in OpenSSL. However, I am a bit wary since I don't see many people using these algorithms for this purpose. Would also appreciate pointers to any materials discussing this topic in general, since I had trouble finding any.

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• Tracking/Counting Word Frequency

  - by Joel Martinez

  I'd like to get some community consensus on a good design to be able to store and query word frequency counts. I'm building an application in which I have to parse text inputs and store how many times a word has appeared (over time). So given the following inputs: "To Kill a Mocking Bird" "Mocking a piano player" Would store the following values: Word Count ------------- To 1 Kill 1 A 2 Mocking 2 Bird 1 Piano 1 Player 1 And later be able to quickly query for the count value of a given arbitrary word. My current plan is to simply store the words and counts in a database, and rely on caching word count values ... But I suspect that I won't get enough cache hits to make this a viable solution long term. Can anyone suggest algorithms, or data structures, or any other idea that might make this a well-performing solution?

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• How does Photoshop (Or drawing programs) blit?

  - by user146780

  I'm getting ready to make a drawing application in Windows. I'm just wondering, do drawing programs have a memory bitmap which they lock, then set each pixel, then blit? I don't understand how Photoshop can move entire layers without lag or flicker without using hardware acceleration. Also in a program like Expression Design, I could have 200 shapes and move them around all at once with no lag. I'm really wondering how this can be done without GPU help. I don't think super efficient algorithms could justify that? Thanks

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• Matlab - Propagate unit vectors on to the edge of shape boundaries

  - by Graham

  Hi I have a set of unit vectors which I want to propagate on to the edge of shape boundary defined by a binary image. The shape boundary is defined by a 1px wide white edge. I also have the coordinates of these points stored in a 2 row by n column matrix. The shape forms a concave boundary with no holes within itself made of around 2500 points. What would be the best method to do this? Are there some sort of ray tracing algorithms that could be used? Or would it be a case of taking the unit vector and multiplying it by a scalar and testing after multiplication if the end point of the vector is outside the shape boundary. When the end point of the unit vector is outside the shape, just find the point of intersection? Thank you very much in advance for any help!

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• Why does git hash-object return a different hash than openssl sha1?

  - by user657606

  Context: I downloaded a file (Audirvana 0.7.1.zip) from code.google to my Macbook Pro (Mac OS X 10.6.6). (current url: http://code.google.com/p/audirvana/downloads/detail?name=Audirvana%200.7.1.zip&can=2&q= ) I wanted to verify the checksum, which for that particular file is posted as 862456662a11e2f386ff0b24fdabcb4f6c1c446a (SHA-1). git hash-object gave me a different hash, but openssl sha1 returned the expected 862456662a11e2f386ff0b24fdabcb4f6c1c446a. The following experiment seems to rule out any possible download corruption or newline differences and to indicate that there are actually two different algorithms at play: $ echo A > foo.txt $ cat foo.txt A $ git hash-object foo.txt f70f10e4db19068f79bc43844b49f3eece45c4e8 $ openssl sha1 foo.txt SHA1(foo.txt)= 7d157d7c000ae27db146575c08ce30df893d3a64 What's going on?

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• Optimizing a Parking Lot Problem. What algorithims should I use to fit the most amount of cars in th

  - by Adam Gent

  What algorithms (brute force or not) would I use to put in as many cars (assume all cars are the same size) in a parking lot so that there is at least one exit (from the container) and a car cannot be blocked. Or can someone show me an example of this problem solved programmatically. The parking lot varies in shape would be nice but if you want to assume its some invariant shape that is fine. Another Edit: Assume that driving distance in the parking lot is not a factor (although it would be totally awesome if it was weighted factor to number of cars in lot). Another Edit: Assume 2 Dimensional (no cranes or driving over cars). Another Edit: You cannot move cars around once they are parked (its not a valet parking lot). I hope the question is specific enough now.

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• grouping objects to achieve a similar mean property for all groups

  - by cytochrome

  I have a collection of objects, each of which has a numerical 'weight'. I would like to create groups of these objects such that each group has approximately the same arithmetic mean of object weights. The groups won't necessarily have the same number of members, but the size of groups will be within one of each other. In terms of numbers, there will be between 50 and 100 objects and the maximum group size will be about 5. Is this a well-known type of problem? It seems a bit like a knapsack or partition problem. Are efficient algorithms known to solve it? As a first step, I created a python script that achieves very crude equivalence of mean weights by sorting the objects by weight, subgrouping these objects, and then distributing a member of each subgroup to one of the final groups. I am comfortable programming in python, so if existing packages or modules exist to achieve part of this functionality, I'd appreciate hearing about them. Thank you for your help and suggestions.

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• Framework/tool for processing C++ unit tests with numerical output

  - by David Claridge

  Hi, I am working on a C++ application that uses computer vision techniques to identify various types of objects in a sequence of images. The (1000+) images have been hand-classified, so we have an XML file for each image containing a description of where the objects are actually located in the images. I would like to know if there is a testing framework that can understand/graph results from tests that are numeric, in this case some measure of the error in the program's classification of the images, rather than just pass/fail style unit tests. We would like to use something like CDash/CTest for running these automated tests, and viewing over time how improvements to the vision algorithms are causing the images to be more correctly classified. Does anyone know of a tool/framework that can do this?

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• Programming tutorials for people with zero experience

  - by www.aegisub.net

  A friend of mine is interested in learning how to program computers, but she knows nothing about programming. I suggested that Python might be a good language to start with, but after some googling, I couldn't find any tutorials that covered both programming and Python in an adequate way. I don't want her to go through the tiresome "learn algorithms in pseudocode first" routine. Instead, I'd like a tutorial that will explain the basic ideas while working towards a real goal, e.g. a very simple console game. Does anyone know of any such tutorials? Do you think that I'm mistaken in how I'm handling this? Is Python a bad choice? I know that something like C, C++ or Java won't work - too many details will be very counterproductive. On the other hand, I think that Lisp might be too mathematical and abstract. Python, on the other hand, will let her even do something like coding primitive graphical games in a short period of time.

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• How can I compute the average cost for this solution of the element uniqueness problem?

  - by Alceu Costa

  In the book Introduction to the Design & Analysis of Algorithms, the following solution is proposed to the element uniqueness problem: ALGORITHM UniqueElements(A[0 .. n-1]) // Determines whether all the elements in a given array are distinct // Input: An array A[0 .. n-1] // Output: Returns "true" if all the elements in A are distinct // and false otherwise. for i := 0 to n - 2 do for j := i + 1 to n - 1 do if A[i] = A[j] return false return true How can I compute the average cost (i.e. number of comparisons for a given n) for this algorithm? What is a reasonable assumption about the input?

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• How to program a connection pool?

  - by the_drow

  Is there a known algorithm for implementing a connection pool? If not what are the known algorithms and what are their trade-offs? What design patterns are common when designing and programming a connection pool? Are there any code examples implement a connection pool using boost.asio? Is it a good idea to use a connection pool for presisting connections (not http)? How is threading related to connection pooling? When do you need a new thread?

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• Realtime processing and callbacks with Python and C++

  - by Doughy

  I need to write code to do some realtime processing that is fairly computationally complex. I would like to create some Python classes to manage all my scripting, and leave the intensive parts of the algorithm coded in C++ so that they can run as fast as possible. I would like to instantiate the objects in Python, and have the C++ algorithms chime back into the script with callbacks in python. Something like: myObject = MyObject() myObject.setCallback(myCallback) myObject.run() def myCallback(val): """Do something with the value passed back to the python script.""" pass Will this be possible? How can I run a callback in python from a loop that is running in a C++ module? Anyone have a link or a tutorial to help me do this correctly?

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• Tree + Recursion..

  - by RBA

  Hi.. I came across an article on Binary Trees Search . It uses intensive Recursive Algorithms.. I am just so confused with these stuff.. Please guide my path so as I understand these problems at ease, or any good website to read about recursion first and then solving these problems.. Please share your experience on it.. Its very urgent, and I want to learn these concepts as soon as possible.. Thankss... Regards.

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• Include an interface from the same package (Java)

  - by DashRantic

  Hi, I'm new to Java (C++ guy myself) and am trying to compile a simple program (testing different random number algorithms) in Java. I have an interface that I want to use to implement another class with, both of these items are in the same package. So I have two files right now in my "Random" package directory--"RandomInterface.java" and "RandomTest1.java" (which implements RandomInterface). I can use javac to compile RandomInterface.java just fine, but I get the following error when I then try to compile RandomTest1: RandomNew.java:3: cannot find symbol symbol: class RandomClass public class RandomNew implements RandomClass ^ 1 error I declare both files to be part of the same package (Random) as the first line of each file. What do I need to do to include the RandomInterface class into the compile command for RandomTest1? Thanks!

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• How to protect against GHC7 compiled programs taking all memory?

  - by Petr Pudlák

  When playing with various algorithms in Haskell it often happens to me that I create a program with a memory leak, as it often happens with lazy evaluation. The program taking all the memory isn't really fun, I often have difficulty killing it if I realize it too late. When using GHC6 I simply had export GHCRTS='-M384m' in my .bashrc. But in GHC7 they added a security measure that unless a program is compiled with -rtsopts, it simply fails when it is given any RTS option either on a command line argument or in GHCRTS. Unfortunately, almost no Haskell programs are compiled with this flag, so setting this variable makes everything to fail (as I discovered in After upgrading to GHC7, all programs suddenly fail saying "Most RTS options are disabled. Link with -rtsopts to enable them."). Any ideas how to make any use of GHCRTS with GHC7, or another convenient way how to prevent my programs taking all memory?

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• How to find root cause for "too many connections" error in MySQL/PHP

  - by Nir

  I'm running a web service which runs algorithms that serve millions of calls daily and run some background processing as well. Every now and than I see "Too many connections" error in attempts to connect to the MySQL box" for a few seconds. However this is not necessarily attributed to high traffic times or anything I can put my finger on. I want to find the bottleneck causing it. Other than in the specific times this happens the server isn't too loaded in terms of CPU and Memory, and has 2-3 connections (threads) open and everything works smoothly. (I use Zabbix for monitoring) Any creative ideas on how to trace it?

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