MATLAB is a high-level language and interactive programming environment developed by MathWorks. It is the foundation for a number of other tools, including Simulink and various toolboxes that extend the core capabilities.
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12 views
Matlab bins with two features: calculation and plotting
I have the following code in Matlab, which is supposed to do what I asked in this SO question. The idea is to:
Divide the temperature deadband of each agent (they are different between agents) into ...
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0answers
26 views
fftshift implementation for OpenCV
I'm trying to implement fftshift from matlab for OpenCV. Can you please review the correctness of my algorithm? Have I missed something? Also, is there a better and faster way to do it?
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0answers
45 views
Simple Priority Queue
I am trying to implement A* search on a grid in MATLAB. I am currently using a priority queue class I found here, but it's a bit slow. I tried to write this simple priority queue class in MATLAB:
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7 views
4
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1answer
77 views
Large Matrix Square Difference Means
I try to transfere Matlab calculation to C and call it using .mex for speed gains. My goal is to perform for a matrix \$ B\$ which has roughly the dimension 10000x1000
\$
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1answer
35 views
Optimize matlab triple for loop
I have a large matrix samples, I want to make another matrix sampleProb which is the same size, but modified as below:
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0answers
18 views
Implementation of Logistic Regression
Is this kind of vectorized operations the most efficient way to do this in matlab? Any critics about my code? Am I doing something wrong (i tested several times, I think it works). Notice that I use J ...
3
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1answer
31 views
Integrate the product of four infinite series functions
I wrote the following code to integrate the product of four functions.
Two of the functions are hypergeometric functions and the other two are incomplete gamma functions. I have written each function ...
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0answers
20 views
Iteratively process an identically named file all subdirectories and plot analysis to root directory
This script can successfully go through all of the subdirectories in a root directory, and then process a specific file that exists in all of them and output the file in the root directory as a .png ...
4
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1answer
64 views
Vectorization for temperature simulation
I'm new to Matlab and I would like to know tips in order to reduce the processing time of such program. The scheme of the actual code is very similar to typical C++ code and I would like to vectorize ...
2
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0answers
47 views
Speeding up loop-rich Matlab function to calculate temperature distribution
I would like to speed up this function as much as possible in Matlab.
This is part of a bigger simulation project, and as it is one of the most called functions within the simulation, this is crucial.
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3
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2answers
71 views
Improving Matlab function within big simulation
I have a very big Matlab simulation project in my hands, which I wanted to optimize, since I'm running it many times to tune parameters and the like.
Using Matlab's ...
1
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1answer
50 views
Improving excution time for list and sampling in Python
Here is my code for generating edge list based on Price model algorithm. I think there have two points to reduce execution time:
use proper data type
use faster random sampling
Originally, I used ...
9
votes
1answer
364 views
Counting Words in Files - MATLAB style
For my Matlab class I'm taking, I was given the task to write a function ReadAndCountWords that takes in the name of a text file (specifically from this zip file) ...
3
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1answer
814 views
Run length encoding of vectors in MATLAB: looped version and vectorized version
A project I'm working on requires something akin to run length encoding on a vector in matlab. The data is in the form of a numeric vector, and the output is in the form of two vectors, ...
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0answers
34 views
Simple class container for hdf5 files
I implemented a simple class container for hdf5 files in matlab.
The situation is as follows. Measurement data is saved in hdf5 ...
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0answers
113 views
Efficient C Code Alternative to MATLAB's im2col
The function im2col in MATLAB is very useful to vectorize Patch based Image Processing algorithms.
The problem is the function isn't optimized and doesn't use C ...
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2answers
121 views
Using brute force to find an energy optimal path for a given amount of time
The code below implements a brute force method to find an energy optimal path for a given amount of time t_aim using recursion (the recursion function is ...
4
votes
2answers
3k views
Trapezoidal rule to approximate the integral of x^2
I've implemented the trapezoidal rule to compute the integral for a function \$x^2\$. I would like to see another style of the same code. It seems Matlab hates for a matrix to be expanded without ...
2
votes
2answers
110 views
90 year data simulation in need of performance increase
I developed some code for my masters project that will simulate 90 years daily data using 1000 different data sets. The code is working fine and gives the correct output that I wanted but the ...
2
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0answers
68 views
Kullback-Leibler (KL) distance between inside and outside contour code
I am trying implement the distance measurement between two distributions. The detail is described in here and input image . Let short summarize the idea of the paper:
The input image is divided ...
4
votes
1answer
128 views
Vectorize Matlab sum
I have the following Matlab function:
function [res] = a3_funct(x)
res = 0;
for i = 1:size(x,1)
res = res + abs(x(i))^(i+1);
end
end
It's ...
3
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0answers
396 views
Satellite orbit simulation in Matlab using Runge Kutta 4
I have a satellite orbit simulation in Matlab (Using Runge Kutta 4). It seems ugly and I don't know how to fix it.
fx.m file:
function v = fx(t,x,vx)
v = vx;
...
8
votes
1answer
126 views
Verifying boardgame mathematics with MATLAB
I recently bought this math-based boardgame for my little cousins, and am now trying to verify its design with some MATLAB code. The relevant parts of the game are:
A board with numbers from 1 to ...
2
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0answers
34 views
Avoiding boundaries if-cases when filtering image matrix
I have the following MATLAB Code which I want to optimize.
It's related to an image matrix (2D) which I want to filter.
Though it is MATLAB code, the same problem would arise in C code.
The problem ...
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0answers
42 views
Why does lu-factorization make my program slower?
I'm trying to calculate the smallest eigenvalue of the matrix A by using the "inverted exponentiation method" (see the code). I manage to find the smallest eigenvalue, but when I try to optimize the ...
2
votes
1answer
46 views
Less For, more MATLABesque?
I have written a piece of MATLAB code that (hopefully) calculates CECT. I have two matrices of psychophysiological measures - one for brain data, one for heart rate; both are of the format epochs * ...
3
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1answer
50 views
Using the Return Value of a Function to Select an Element in a Struct Array
I'm learning MATLAB (still trying to "think in vectors") and have the following piece of code:
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1answer
169 views
Creation of MxM matrix: Python version much slower than Matlab version
I have written the same code in Python (NumPy) and in Matlab, and I tried to use the same structure for both language and follow the same procedure. Now my problem is that when I run my code in Python ...
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0answers
296 views
Stochastic gradient descent squared loss
I have implemented stochastic gradient descent in matlab and I would like to compare my results with another source but the error I am getting is higher (I am using squared error). I am worried I am ...
4
votes
1answer
4k views
K-nearest neighbours in MATLAB
I implemented K-Nearest Neighbours algorithm, but my experience using MATLAB is lacking. I need you to check the small portion of code and tell me what can be improved or modified. I hope it is a ...
2
votes
1answer
434 views
Parsing MWNumericArray to C# code optimization
This is my function returning matrices from Matlab. This code run very slowly.
I was trying to use Parallel.For in-order to run it in parallel threads but I got ...
2
votes
0answers
97 views
Increasing speed of parity check matrix
The code runs fine and takes 100s to complete it for 5 iteration. I need to reduce it to take less time with the same number of iterations.
h = 324 by 648 matrix
The code is that of FFT Belief ...
4
votes
2answers
70 views
What's the fastest way to get the points I want out of a huge blob?
In MATLAB I have a set of 5393280 points in the form of a decimal-valued vector (x,y,z). How do I represent them in a way that I can quickly collect all the points within some rectangular x-y domain?
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1answer
79 views
How can these if-else statements be made more efficient?
I am using the cURL tool in MATLAB 2013b with Ubuntu to download a whole bunch of files. The files have one of three possible versions: 1.0.0, 2.0.0, or 2.1.0. Using the HTTP, I first check the ...
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3answers
2k views
Speeding up this k-nearest neighbors implementation
I have implemented kNN (k-nearest neighbors) as follows, but it is very slow. I want to get an exact k-nearest-neighbor, not the approximate ones, so I didn't use the FLANN or ANN libraries.
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votes
3answers
86 views
Is this a valid way of computing autocorrelation?
I am a beginner in Digital Signal Processing and I was trying to compute and plot an autocorrelation.
I've wrote this piece of code:
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1answer
78 views
Speeding up repetitive initialisation with structured data?
I need to speed up this code: it creates a multilinear function. I considered the below methods but no idea which with the largest benefit.
replacing dummy variables with things such as anonymous ...
2
votes
0answers
80 views
Fitness function
I have a fitness function, where inputs x1 to x14 have values between 1:4. Is there a way to make this more efficient? Any ...
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3answers
75 views
Using matlabpool: Is my embedding correct?
A general question: For using matlabpool, I write the line
matlabpool open local 12;
as the first line in my code and the line:
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1answer
832 views
Matlab - Fastest way to parallel read many files line by line?
I have a few hundred files in a directory that I need to read in parallel. Namely, the files that have the same name, but different file extensions (.a and .b), but they're pretty much plain text ...
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2answers
584 views
Rational Approximation for e with Matlab
I've written a program that calculates the best rational approximation for e with a 1, 2, 3, 4, 5, and 6 digit denominator respectively (on Matlab). For a 5-digit denominator it takes about a minute. ...
3
votes
1answer
1k views
Build a combinatorial matrix from two vectors
I want to define a matrix of values with a very simple pattern. I've achieved it with the code below but it's ugly - very difficult to read (I find) and surely not as optimal, in terms of performance, ...
2
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2answers
172 views
Matlab: Can this triple loop be simplified or eliminated
Matlab profiler throws this horrible bottleneck which is called 700000 times:
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1answer
3k views
5
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2answers
1k views
Python / Numpy running 15x slower than MATLAB - am I using Numpy effeciently?
Here is some code I wrote in Python / Numpy that I pretty much directly translated from MATLAB code. When I run the code in MATLAB on my machine, it takes roughly 17 seconds. When I run the code in ...
5
votes
2answers
538 views
Drawing random smooth lines contained within a square
I'm trying to write a matlab function that creates random, smooth trajectories in a square of finite side length. Here is my current attempt at such a procedure:
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6
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1answer
627 views
Using homogeneous coordinates to rotate an image
Currently, I have this code snippet, but it's a little bit slow:
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3
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1answer
159 views
5
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1answer
158 views
Processing random matrices
I am doing my research about scheduling by using Matlab. I am a new Matlab user and I have a problem with time execution of my following code:
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