Questions tagged [matlab]

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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21
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5answers
1k views

Benchmarks of various scientific programming languages for theoretical modelling

For a theoretical modelling course for biology students, I am trying to decide which would be the best technical programming language for doing evolutionary simulations in terms of elegance and ...
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1answer
128 views

Horizontally concatenating the entries of two matrices, and padding with NaNs

I have two matrices a and b that have, on each line, some values (null or not) and then a bunch of zeros at the end. I want to ...
5
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2answers
91 views

Extract the largest value for each day from a matrix

I have a matrix in which the right-most elements are repeated YYYYMMDD dates in descending order, for example: ...
2
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1answer
375 views

Verification of Sudoku boards

A valid Sudoku board has the following properties The board must be square (n-by-n). Let m = sqrt(n) All rows must contain the numbers 1-n All columns must ...
0
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1answer
49 views

Assign values to a matrix based on the location of non-zero elements in another matrix

I have a matrix, A containing ones and zeros. I want to create a new matrix B where the non-zero elements are in the same ...
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1answer
121 views

Merging two square matrices

I would like to optimize a snippet of code, which uses a multiple nested if statements. I am looking for a formula to make it as a combination of multiple arrays ...
1
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1answer
987 views

Pattern recognition and machine learning - Bernoulli mixture model

I have been reading the book Pattern Recognition and Machine Learning (Bishop) for a while, and recently I came across this figure, which was created using Bernoulli mixture model on the MNIST dataset:...
4
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1answer
120 views

Biometric matching score calculator

I'm working on a biometric matching system and I would like to have few suggestions regarding vectorizing the following code: ...
4
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2answers
114 views

Vectorizing a polar coordinate conversion loop in a fingerprint-matching process

I am working on a fingerprint matching technique and it takes a lot of computation time to obtain the result. I am trying to implement the matching process given in A Minutia Matching Algorithm in ...
5
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1answer
132 views

Computing the total different between a pixel and its neighborhood

I have C++ code which written for mex in MATLAB. It used to compute the total different between a pixel and its neighborhood (8 neighborhood in my code). The code ran and gave me an expected result. ...
7
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2answers
591 views

Visualizing Newton-Raphson method for finding zeroes of a function

I have created a program to visualize the working of Newton-Raphson method to find the zeroes of a function: newton.m: ...
2
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1answer
59 views

Quickly Evaluating MANY matlabFunctions

This post builds on my post about quickly evaluating analytic Jacobian in Matlab. The key difference is that I am now working with the Hessian and I have to evaluate close to 700 matlabFunctions (...
3
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2answers
684 views

Converting decimal to Roman numerals using MATLAB

I have written a MATLAB function that converts decimals into Roman numerals. ...
3
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1answer
72 views

Vectorising orthogonal-triangular decomposition for 3D matrix

I am trying to optimise the computation time of my code (for the second time after a first optimisation that gives very good results). Currently, this code is very time-consuming depending on the size ...
4
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0answers
696 views

Reading cell array of vectors with h5py

I have a data stored in .mat files, each .mat contains a cell array of vectors of length ~70. I'm trying to read these .mat files in to Python with h5py, but reading just 1000 cells takes about 7 ...
6
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1answer
441 views

Segmenting brain images (Dicom format) using region-growing algorithm

I have a list of images in a folder where num denotes the index of image and I used num to run the iterations in a "for loop". ...
14
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2answers
2k views

A* search in MATLAB

I have implemented A* search in MATLAB, but I am looking for ways to increase the speed and optimize it. I have tried using a priority queue but I found it doesn't work that well, so I am using a ...
8
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1answer
145 views

Matlab Computer Vision

The code below takes a video as input (a drop onto a fabric surface) and I want it to return the area of the drop. Currently the code works, but I'm no Matlab expert, and wrote it entirely through ...
3
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2answers
425 views

Weighted dice with n faces

Here you find some code that returns the value of a multivariate Bernoulli density function - for a dice with n faces, where each face has its weight (weight must be positive reals, not necessarily ...
2
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0answers
493 views

Linear interpolation Matlab to C++

I don't have a strong mathematics/Matlab background. I would like to convert this Black level correction function from Matlab to C++. Please comment about on the code style and correctness of my ...
4
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1answer
81 views

Function that reorders the columns of a matrix

The objective: Given an m by n matrix, I have written a function in Matlab that reorders the columns of the matrix to output linearly independent columns; other/redundant columns. Basically, it just ...
2
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1answer
106 views

Searching for log entries in SQLite that involve a particular IP subnet

This reads a huge database (SQLite) and extract any IP address similar to ip_base: ...
3
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1answer
1k views

Currying in Matlab

As MATLAB has a hard maximum of 10 input arguments it's possible, but ugly, to implement a curry function in this manner: ...
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1answer
130 views

Matlab to C++ percentile clipping

I have a 2D matrix in Matlab and I want to convert the Matlab code into C++. In C++ I have int* channel_gr. The commented code is the original Matlab code. Is ...
0
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1answer
66 views

Plotting a trigonometric function appears to be too slow

This calculates the mobility and it's derivative of one element. If I calculate with 1 value of w, it's very fast. ...
2
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1answer
155 views

Dealing with input and output in Matlab

I just wrote a program which performed some elementary set operations as you can see below. It's the first time I have used input and output of text files so I am mainly looking for critique on that, ...
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0answers
57 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 <...
3
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1answer
2k 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? ...
4
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2answers
3k 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: <...
5
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1answer
116 views

Mean of the squares of differences for a large matrix

I have tried to obtain speed gains by transferring Matlab calculations to C and call it using .mex. My goal is to operate on a matrix \$B\$ which has roughly the dimension 10000x1000 $$ \frac{1}{\...
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1answer
401 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: ...
5
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1answer
126 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
169 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 ...
1
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0answers
48 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 ...
5
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1answer
97 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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1answer
114 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. ...
7
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3answers
257 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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2answers
148 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 ...
10
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1answer
2k 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
4k 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, ...
1
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0answers
103 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 ...
3
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1answer
659 views

Implementation of 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 ...
1
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2answers
163 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 ...
5
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2answers
26k 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 ...
6
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3answers
176 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
188 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 into ...
5
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1answer
461 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 ...
4
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0answers
2k 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
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1answer
195 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 100 ...
3
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1answer
69 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 ...