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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1/x scaled x axis in matlab plot [migrated]

What is the matlab way to create transformed scaling on the x axis? I use this workaround to plot an 1/x scaled axis. The problem here is, that plot does not plot ...
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13 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
11 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 ...
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0answers
27 views

Counting the true number of comparisions in an insertion sort

I'm trying to count the number of comparisons in insertion sort. Here is my code is MATLAB: ...
3
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1answer
29 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
14 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
61 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
40 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. ...
3
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2answers
66 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 ...
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1answer
49 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
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1answer
262 views

Counting Words in Files - MATLAB style

Note: this question may seem quite large, but the code to review is actually quite short For my Matlab class I'm taking, I was given the task to write a function ...
3
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1answer
589 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
99 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
119 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
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2answers
2k 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
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2answers
106 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
62 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
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1answer
119 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
347 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; ...
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1answer
120 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
41 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
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1answer
45 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
165 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
285 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
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1answer
3k 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
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1answer
384 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
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0answers
96 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
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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
77 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. ...
2
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3answers
84 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
77 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 ...
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0answers
75 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
74 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: ...
1
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1answer
793 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
559 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
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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, ...
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2answers
165 views

Matlab: Can this triple loop be simplified or eliminated

Matlab profiler throws this horrible bottleneck which is called 700000 times: ...
0
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1answer
3k views

2D convolution in matlab

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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
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2answers
502 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: ...
6
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1answer
579 views

Using homogeneous coordinates to rotate an image

Currently, I have this code snippet, but it's a little bit slow: ...
3
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1answer
156 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: ...
3
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1answer
177 views

Calculate FFT from windowed time-based signal

I have a time-based signal (Raw signal) sampled at 6 MHz and need to analyze it in freq. domain. I'm learning DSP and this is very first time I work with DSP. Could you please help to check if this ...
1
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1answer
458 views

Computing the sum of squared differences of the concentration profile

About Data: I have a 3D data (100x100x20) of space and time (c) where first 2 dimensions are concentration values along space while 3rd dimension contains ...
2
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1answer
270 views

Is this a valid usage of structure assignment in C?

Q: Please comment on the usage of structures and structure assignment operations in C I am working on converting a MATLAB program to C using BLAS and LAPACK for linear algebra support. The MATLAB ...