Tagged Questions

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.

31 views

Vectorizing Two Sample Kolmogorov-Smirnov test

I'm implementing the Two-sample Kolmogorov-Smirnov test in MATLAB. I must admit I know very little of formal statistics and was simply trying to implement the description in wikipedia's page. Right ...
27 views

Matlab implementation of Needleman-Wunsch algorithm

This code (an implementation of the path finding Needleman-Wunsch algorithm), given two sequences, correctly aligns and calculates the similarity of them. For example, given two sequences: AAA,CCC ...
648 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 ...
102 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 ...
63 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: ...
63 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 ...
29 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 ...
115 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 ...
165 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:...
75 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: ...
71 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 ...
84 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. ...
72 views

Inpainting algorithm using conjugate gradient for colored images using Matlab

I am currently working on an inpainting algorithm : the input is a picture, I apply a Mask (random disposition of dark pixels) and then the algorithm tries to recover the original picture using the "...
92 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: ...
49 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 (...
255 views

Decompose polarimetric SAR covariance matrices in MATLAB

I want to apply the following code on 3 images of the sizes 676×718, 1430×1440, and 5576×9444, but the code is too slow even for the 676×718 image. ...
65 views

Converting decimal to Roman numerals using MATLAB

I have written a MATLAB function that converts decimals into Roman numerals. ...
64 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 ...
102 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 ...
73 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". ...
68 views

Computing the curvature of a 2D image

I have some MATLAB code that computes the curvature of a 2d image. It computes it iteratively using forward and backward differences. Could you offer some tips for how I can optimize this code? ...
195 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 ...
96 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 ...
68 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 ...
129 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 ...
75 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 ...
32 views

Implement Chambolle dual formulation method in matlab

I would like to implement an Chambolle dual formulation method. The method can be summarize as following This is my implementation in matlab. However, it does not give true result (but combine ...
63 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: ...
300 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: ...
68 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 ...
62 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. ...
76 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, ...
45 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 <...
634 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? ...
727 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: <...
103 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}{\...
232 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: ...
73 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 ...
48 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 ...
42 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 ...
91 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 ...
100 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. ...
155 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 ...
101 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 ...
1k 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) ...
2k 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, ...
76 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 ...
301 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 ...
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 ...