Tagged Questions

An algorithm is a sequence of well-defined steps that defines an abstract solution to a problem. Use this tag when your issue is related to algorithm design.

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116 views

Can't get clean output in my MATLAB implementation of Canny-Deriche

My code so far is: function imgg = derichefilter1(x, k, a, b, c) osize = size(x); x = double(x); a = double(a); b = double(b); c = double(c); k = double(k); y1 = zeros(osize(1),osize(2)); y2 = ...
5
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166 views

Iterators concatenation performance

Just below, the code of Iterator's ++ method: /** Concatenates this iterator with another. * * @param that the other iterator * @return a new iterator that first yields ...
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146 views

Algorithm for finding circular mappings of maximal size

I have nine sets of 500 objects each. Although the sets are independent, I assume that the sets share a core of common objects. However, one and the same object may have a different name (index) ...
4
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154 views

GLSL-ES Random grainy noise with FP16 limit

I am trying to write a compact and simple noise function with a strictly FP16 limit. This is with what I came out so far, but I think somewhere on the operation the number gets too small for fract or ...
4
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0answers
214 views

Part 2 Resilient backpropagation neural network

This is a follow-on question to this post. For a given neuron, I'm unclear as to how to take a partial derivative of its error and the partial derivative of it's weight. Working from this web page, ...
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396 views

Generalized Load Balancing (GLB) using Linear Programming (LP)

In one of my project - I have a scenario where I need to implement an algorithm capable of doing load balancing. Now, unlike the general load balancing problem present in CS theory (which is NP hard) ...
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312 views

Clojure DAG (Bayesian Network)

I would like to build a Bayesian Network in clojure, since I haven't found any similar project. I have studied a lot of theory of BN but still I can't see how implement the network (I am not what ...
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247 views

Distributed local clustering coefficient algorithm (MapReduce/Hadoop)

I have implemented MapReduce paradigm based local clustering coefficient algorithm. However I have run into serious troubles for bigger datasets or specific datasets (high average degree of a node). I ...
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88 views

algorithm to dynamically monitor quantile(s)

I want to estimate the quantile of some data. The data is so huge that it won't fit in memory. And new data keeps coming in. Does anyone know an algorithm to monitor the quantile(s) of the data ...
3
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0answers
72 views

How to locate data-item position in the hierarchy?

I need to develop an algorithm that can locate data item position in some hierarchy. I have hierarchy that classifies elements of some dataset. Hierarchy is taxonomic - top element is the most generic ...
3
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0answers
98 views

Automatic enhancement of scanned images

I'm developing a routine for automatic enhancement of scanned 35 mm slides. I'm looking for a good algorithm for increasing contrast and removing color cast. The algorithm will have to be completely ...
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0answers
132 views

Increase set of numbers so that XOR sum is 0

I need some help with a problem that I have reduced to the following. I have N 30 bit numbers, such that the combined XOR of all of them is non-zero. I need to add a non-negative (0 or more) value to ...
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152 views

Extendible hashing - most significant bits

I want to write extendible hashing. On wiki I have found good implementation in python. But this code uses least significant bits, so when I have hash 1101 for d = 1 value is 1 and for d = 2 value is ...
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41 views

What's the most storage efficient Octree structure for reconstruction?

I've coded a full octree implementation without too much optimization for 3D reconstruction, however, the tree structure contains too many pointers, and cannot support more than 256^3 voxels. ...
2
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0answers
121 views

Compute next hop routing table from adjacency matrix using Dijkstra's algorithm - alg. not stopping

I am trying to determine a next hop routing table using an adjacency matrix. Each node knows the full adjacency matrix for that topology. I have found previous posts explaining how to do it, however, ...
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0answers
35 views

Solr Document Tagging

I am working with Solr and my need is to tag documents that are indexed based on the content that resides within the documents. I am thinking of using KEA for extracting key phrases. So i wanted to ...
2
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0answers
65 views

retrieving and storing route Map data

I am working on a project where the requirement is to retrieve map related data for a specific source and destination. On each of the future requests this already fetched information which is cached ...
2
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0answers
89 views

Flow Free Like Random Level Generation with only one possible solution?

I've implemented the algorithms marked as the correct answer in this question: What to use for flow free-like game random level creation? However, using that method will create boards that may have ...
2
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0answers
106 views

Drug Delivery Economics : Max Path of Length k?

I am a drug dealer with a map of delivery routes that are each worth a certain amount. But I can't cover the whole area, I just have to fight out my little bit of turf. However, I can choose which bit ...
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49 views

Pyephem Algorithms Reference

I have never used pyephem before, and I'm not expert in satellite positioning. I'd like to exploit pyephem to calculate the position of a satellite using TLE. I have to do something very easy, like ...
2
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0answers
127 views

Recursive Relation Help for dynamic programming 2d Plane algorithm

So I've been working on an algorithm. The task I'm trying to accomplish is: consider a 2D plane there are targets that are randomly distributed between a y upper bound and lower bound. This set is T. ...
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0answers
60 views

More detailed explanation of a range tree, maybe with c++ implementation?

I'm trying to learn more data structures for programming contests. I've looked at/implemented a segment tree, but a lot of solutions on topcoder/other forums references a "range tree". None of these ...
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288 views

What is a sensible algorithm to generate the letters in Letterpress iOS game?

I've been playing Letterpress a lot lately. The aim of the game is pretty much to score as many blue tiles as possible by making words out of the letters on the board. When you play your word, ...
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0answers
99 views

Running out of memory using Node.js to optimise route pairings with mongodb database

Ive been trying to crack this for days, any help would be GREATLY appreciated. Basically im trying to iterate through this array of destination pairings and see if the overall distance can be ...
2
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0answers
152 views

Range reduction for trigonometric functions

I'm trying to implement range reduction for trigonometric functions. I found this paper http://www.computer.org/csdl/proceedings/pcspa/2010/4180/00/4180b048-abs.html which talks about using 64-bit ...
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0answers
128 views

3d Fenwick tree

I have a three-dimensional fenwick tree data structure. I need to calculate sum on some segment from (x0, y0, z0) to (x, y, z) What is the formula for inclusion-exclusion? For instance, for 2D ...
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181 views

Udi Manber and Gene Myers Method

I have a suffix array SA, and an array L that stores the length of LCP (longest common prefix) between two consecutive suffixes, i.e. L[i]=LCP(SA[i-1],SA[i]) where 1<=i<=|SA| It's also ...
2
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0answers
193 views

Good place to find different procedual and non-procedual generation algorithms

Does anyone know a good place to find different algorithms for generating worlds, universes, maps, etc. ? I have searched several places but most of the times the pages only tell you about the theory ...
2
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0answers
127 views

Where can I get S. Heymann's GPU Implementation of SIFT Algorithm?

S. Heymann implemented SIFT algorithm on GPU in 2007, his paper is here http://wscg.zcu.cz/wscg/Papers_2007/Full/G03-full.pdf Now I need to run his code for a comparison with my implementation. It ...
2
votes
0answers
61 views

Distance Based Metric For Locally Scaled Difference of Distance Between Moving Points

I am trying to form a metric to model the following scenario. Given various combinations of triples of points (calls those triples abc) in euclidean space, where all points are moving independently ...

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