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

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• Algorithms for finding a numerical record in a list of ordered numbers

  - by Ankur

  I have a list of incomplete ordered numbers. I want to find a particular number with as few steps as possible. Are there any improvements on this algorithm, I assume you can count the set size without difficulty - it will be stored and updated every time a new item is added. Your object is to get your cursor over the value x The first number (smallest) is s, and the last number (greatest) is g. Take the midpoint m1 of the set: calculate is x < m1, If yes then s <= x < m1 If no then m1 < x <= g If m1 = x then you're done. Keep repeating till you find x. Basically dividing the set into two parts with each iteration till you hit x. The purpose is to retrieve a numerical id from a very large table to then find the associated other records. I would imagine this is the most trivial kind of indexing available, are there improvements?

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• Perl vs Python: implementation of algorithms to deal with advanced data structures

  - by user350571

  I'm learning perl and everytime I search for perl stuff in the internet I get some random page with people saying that perl should die because code written in it looks like a lesson in steganography. Then they say that python is clean and stuff like that. Now, I know that those comparisons are always stupid and made by fellows that feel that languages are a extension of their boring personality so, let me ask instead: can you give me the implementation of a widely known algorithm to deal with a data structure like red-black trees in both languages so I can compare?

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• Searching Techniques/Algorithms for Resources over a given area

  - by Raydon

  I have a flat area with nodes randomly placed on this flat surface. I need techniques which are able to take a starting point, move in a certain way (the algorithm), find nodes and continue searching. I do not have an overall view of the surface (i.e. I cannot see everything), only a limited view (i.e. 4 cells in any direction). Ideally, these methods would be efficient in the way that they work. Any points in the right direction would be greatly appreciated.

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• Where to start when programming process synchronization algorithms like clone/fork, semaphores

  - by David

  I am writing a program that simulates process synchronization. I am trying to implement the fork and semaphore techniques in C++, but am having trouble starting off. Do I just create a process and send it to fork from the very beginning? Is the program just going to be one infinite loop that goes back and forth between parent/child processes? And how do you create the idea of 'shared memory' in C++, explicit memory address or just some global variable? I just need to get the overall structure/idea of the flow of the program. Any references would be appreciated.

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• I am trying to build a list of limitations of all graph algorithms

  - by Jack

  Single Source shortest Path Dijkstra's - directed and undirected - works only for positive edge weights - cycles ?? Bellman Ford - directed - no cycles should exist All source shortest path Floyd Warshall - no info Minimum Spanning Tree ( no info about edge weights or nature of graph or cycles) Kruskal's Prim's - undirected Baruvka's

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• comparison of sorting algorithms

  - by hash5

  When do we prefer a) bucket sort, and b) radix sort over comparison sorts like bubble sort insertion sort selection sort merge sort quick sort?

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• Nesting Patterns Algorithms / Cutting Waste Problem

  - by WedTM

  First off, I'd like to say that I'm already looking into the "Cutting Stock Problem" algorithm, however I feel that I need a bit more clarification, and possibly some help with some of the math (Not my strong point). What I need to do is have an offset pattern that causes the circle to fit in the crevasse created by having the two circular dies sitting next to each other on the previous line, like so: O O O O O O O O O O O O O O O O O I'm hoping someone can point me towards the right algorithm for this! Thanks!

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• Are mathematical Algorithms protected by copyright?

  - by analogy

  I wish to implement an algorithm which i read in a journal paper in my software (commercial). I want to know if this is allowed or not. The algorithm in question is described in http://arxiv.org/abs/0709.2938 It is a very simple algorithm and a number of implementations exist in python (http://igraph.sourceforge.net/) and java. One of them is in gpl another which i got from a different researcher and had no license attached. There are significant differences in two implementations, e.g. second one uses threads and multiple cores. It is possible to rewrite/ (not translate) the algorithm. So can I use it in my software or on a server for commercial purpose. Thanks UPDATE: I am completely aware of copyright on the text of paper, it was published in phys rev E. I am concerned with use of the algorithm, in commercial software. Also the publication means that unless the patent has been already filed. The method has been disclosed publicly hence barring patent in future. Also the GPL implementation is not by authors themselves but comes from a third party. Finally i am not using the GPL implementation but creating my own using C++.

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• SQLAlchemy custom sorting algorithms when using SQL indexes

  - by David M

  Is it possible to write custom collation functions with indexes in SQLAlchemy? SQLite for example allows specifying the sorting function at a C level as sqlite3_create_collation(). An implementation of some of the Unicode collation algorithm has been provided by James Tauber here, which for example sorts all the "a"'s close together whether they have accents on them or not. Other examples of why this might be useful is for different alphabet orders (languages other than English) and sorting numeric values (sorting 10 after 9 rather than codepoint order.) Is this possible in SQLAlchemy? If not, is it supported by the pysqlite3 or MySQLdb modules, or for any other SQL database modules supported by python for that matter? Any information would be greatly appreciated.

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• Factorial Algorithms in different languages

  - by Brad Gilbert

  I want to see all the different ways you can come up with, for a factorial subroutine, or program. The hope is that anyone can come here and see if they might want to learn a new language. Ideas: Procedural Functional Object Oriented One liners Obfuscated Oddball Bad Code Polyglot Basically I want to see an example, of different ways of writing an algorithm, and what they would look like in different languages. Please limit it to one example per entry. I will allow you to have more than one example per answer, if you are trying to highlight a specific style, language, or just a well thought out idea that lends itself to being in one post. The only real requirement is it must find the factorial of a given argument, in all languages represented. Be Creative! Recommended Guideline: # Language Name: Optional Style type - Optional bullet points Code Goes Here Other informational text goes here I will ocasionally go along and edit any answer that does not have decent formatting.

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• Programming With Markov Algorithms.

  - by Bubba88

  Hello! I Wonder if someone has used Markov Algorithm-based programming system or embedded facility in production or for scientific purpose. I know about 'REFAL' programming language invented a thousand years ago, but it all seems to be dead, so.. Ref: http://en.wikipedia.org/wiki/Markov_algorithm

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• Are mathamatical Algorithms protected by copyright

  - by analogy

  I wish to implement an algorithm which i read in a journal paper in my software (commercial). I want to know if this is allowed or not. The algorithm in question is described in http://arxiv.org/abs/0709.2938 It is a very simple algorithm and a number of implementations exist in python (http://igraph.sourceforge.net/) and java. One of them is in gpl another which i got from a different researcher and had no license attached. There are significant differences in two implementations, e.g. second one uses threads and multiple cores. It is possible to rewrite/ (not translate) the algorithm. So can I use it in my software or on a server for commercial purpose. Thanks

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• Searching in graphs trees with Depth/Breadth first/A* algorithms

  - by devoured elysium

  I have a couple of questions about searching in graphs/trees: Let's assume I have an empty chess board and I want to move a pawn around from point A to B. A. When using depth first search or breadth first search must we use open and closed lists ? This is, a list that has all the elements to check, and other with all other elements that were already checked? Is it even possible to do it without having those lists? What about A*, does it need it? B. When using lists, after having found a solution, how can you get the sequence of states from A to B? I assume when you have items in the open and closed list, instead of just having the (x, y) states, you have an "extended state" formed with (x, y, parent_of_this_node) ? C. State A has 4 possible moves (right, left, up, down). If I do as first move left, should I let it in the next state come back to the original state? This, is, do the "right" move? If not, must I transverse the search tree every time to check which states I've been to? D. When I see a state in the tree where I've already been, should I just ignore it, as I know it's a dead end? I guess to do this I'd have to always keep the list of visited states, right? E. Is there any difference between search trees and graphs? Are they just different ways to look at the same thing?

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• UUID collision risk using different algorithms

  - by Diego Jancic

  Hi Guys, I have a database where 2 (or maybe 3 or 4) different applications are inserting information. The new information has IDs of the type GUID/UUID, but each application is using a different algorithm to generate the IDs. For example, one is using the NHibernate's "guid.comb", other is using the SQLServer's NEWID(), other might want to use .NET's Guid.NewGuid() implementation. Is there an above normal risk of ID collision or duplicates? Thanks!

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• Time Complexities of recursive algorithms

  - by Peter

  Whenever I see a recursive solution, or I write recursive code for a problem, it is really difficult for me to figure out the time complexity, in most of the cases I just say its exponential? How is it exponential actually? How people say it is 2^n, when it is n!, when it is n^n or n^k. I have some questions in mind, let say find all permutations of a string (O(n!)) find all sequences which sum up to k in an array (exponential, how exactly do I calculate). Find all subsets of size k whose sum is 0 (will k come somewhere in complexity , it should come right?). Can any1 help me how to calculate the exact complexity of such questions, I am able to wrote code for them , but its hard understanding the exact time complexity.

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• Linear-time algorithms for sorting vertices in polygon contours

  - by Cheery

  I figured out an algorithm that lets me turn my holed polygons into trapezoids in linear time if I have vertex indices sorted from lowest coordinate to highest. I get simple polygons as contours. They have certain order that might be exploited most of the time. So giving these conditions, is there a near-linear-time algorithm on sorting?

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• Algorithms for finding closest vector

  - by joel

  I have a set of vectors. For a vector in that set I like to find the sub set that is closeest to this vector. What algorithm can do this.

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• Out-of-memory algorithms for addressing large arrays

  - by reve_etrange

  I am trying to deal with a very large dataset. I have k = ~4200 matrices (varying sizes) which must be compared combinatorially, skipping non-unique and self comparisons. Each of k(k-1)/2 comparisons produces a matrix, which must be indexed against its parents (i.e. can find out where it came from). The convenient way to do this is to (triangularly) fill a k-by-k cell array with the result of each comparison. These are ~100 X ~100 matrices, on average. Using single precision floats, it works out to 400 GB overall. I need to 1) generate the cell array or pieces of it without trying to place the whole thing in memory and 2) access its elements (and their elements) in like fashion. My attempts have been inefficient due to reliance on MATLAB's eval() as well as save and clear occurring in loops. for i=1:k [~,m] = size(data{i}); cur_var = ['H' int2str(i)]; %# if i == 1; save('FileName'); end; %# If using a single MAT file and need to create it. eval([cur_var ' = cell(1,k-i);']); for j=i+1:k [~,n] = size(data{j}); eval([cur_var '{i,j} = zeros(m,n,''single'');']); eval([cur_var '{i,j} = compare(data{i},data{j});']); end save(cur_var,cur_var); %# Add '-append' when using a single MAT file. clear(cur_var); end The other thing I have done is to perform the split when mod((i+j-1)/2,max(factor(k(k-1)/2))) == 0. This divides the result into the largest number of same-size pieces, which seems logical. The indexing is a little more complicated, but not too bad because a linear index could be used. Does anyone know/see a better way?

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• Flow charts and algorithms

  - by Dave

  Hello there, I am from a networking background and completely new to algorithm and flow charts, so could you please assist me with the following? Draw flow charts for the following algorithmss: State whether a number entered at the keyboard is even or odd. Calculate the mean of a five numbers entered by the user from the keyboard Count the number of characters and the number of words that are in a text file Many thanks in advance!

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• algorithms that destruct and copy_construct

  - by FredOverflow

  I am currently building my own toy vector for fun, and I was wondering if there is something like the following in the current or next standard or in Boost? template<class T> void destruct(T* begin, T* end) { while (begin != end) { begin -> ~T(); ++begin; } } template<class T> T* copy_construct(T* begin, T* end, T* dst) { while (begin != end) { new(dst) T(*begin); ++begin; ++dst; } return dst; }

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• Algorithms for finding the intersections of intervals

  - by tomwu

  I am wondering how I can find the number of intervals that intersect with the ones before it. for the intervals [2, 4], [1, 6], [5, 6], [0, 4], the output should be 2. from [2,4] [5,6] and [5,6] [0,4]. So now we have 1 set of intervals with size n all containing a point a, then we add another set of intervals size n as well, and all of the intervals are to the right of a. Can you do this in O(nlgn) and O(nlg^2n)?

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• How do 20 questions AI algorithms work?

  - by Daddy Warbox

  Simple online games of 20 questions powered by an eerily accurate AI. How do they guess so well?

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• complexity of algorithms

  - by davit-datuashvili

  i have question what is complexity of this algorithm public class smax{ public static void main(String[]args){ int b[]=new int[11]; int a[]=new int[]{4,9,2,6,8,7,5}; for (int i=0;i int m=0; while (m int k=a[0]; for (int i=0;i k && b[a[i]]!=1){ b[a[i]]=1; } } m++; } for (int i=0;i for (int j=0;j //result=2 4 5 6 7 8 9 } } ?

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• algorithms undirected graph twodegree[]

  - by notamathwiz

  For each node u in an undirected graph, let twodegree[u] be the sum of the degrees of u's neighbors. Show how to compute the entire array of twodegree[.] values in linear time, given a graph in adjacency list format. This is the solution for all u ? V : degree[u] = 0 for all (u; w) ? E: degree[u] = degree[u] + 1 for all u ? V : twodegree[u] = 0 for all (u; w) ? E: twodegree[u] = twodegree[u] + degree[w] can someone explain what degree[u] does in this case and how twodegree[u] = twodegree[u] + degree[w] is supposed to be the sum of the degrees of u's neighbors?

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• How to choose an integer linear programming solver ?

  - by Cassie

  Hi all, I am newbie for integer linear programming. I plan to use a integer linear programming solver to solve my combinatorial optimization problem. I am more familiar with C++/object oriented programming on an IDE. Now I am using NetBeans with Cygwin to write my applications most of time. May I ask if there is an easy use ILP solver for me? Or it depends on the problem I want to solve ? I am trying to do some resources mapping optimization. Please let me know if any further information is required. Thank you very much, Cassie.

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