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.
2
votes
0answers
25 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
votes
2answers
56 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 ...
0
votes
1answer
35 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
136 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
votes
1answer
235 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
vote
0answers
32 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 ...
1
vote
0answers
71 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 ...
1
vote
2answers
115 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
934 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
105 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
votes
0answers
53 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
111 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
votes
0answers
276 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
118 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
votes
0answers
31 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 ...
1
vote
0answers
36 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
44 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
votes
1answer
46 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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0
votes
1answer
145 views
My Python code (for creation of MxM matrix) is much slower than my 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 ...
0
votes
0answers
265 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
2k 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
288 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
94 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
69 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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1
vote
1answer
76 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 ...
6
votes
3answers
1k 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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2
votes
3answers
79 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:
...
1
vote
1answer
76 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
73 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 ...
1
vote
3answers
71 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
vote
1answer
722 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 ...
1
vote
2answers
509 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
votes
2answers
156 views
Matlab: Can this triple loop be simplified or eliminated
Matlab profiler throws this horrible bottleneck which is called 700000 times:
...
0
votes
1answer
3k views
5
votes
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
454 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
votes
1answer
505 views
how to improve this matlab code using homogeneus coordinates to rotate a matrix?
Currently, I have this code snippet, but it's a little bit slow:
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3
votes
1answer
149 views
5
votes
1answer
156 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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3
votes
1answer
171 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
vote
1answer
445 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
votes
1answer
269 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 ...
2
votes
2answers
1k views
MATLAB and Armadillo, hints on translating
i'm rewriting some Matlab code to c++ using armadillo, a libs for linear algebra. really good libs, IMHO. but i had to translate some matlab construct because armadillo isn't matlab.
i want to share ...
3
votes
1answer
615 views
2
votes
1answer
7k views
Matlab code demonstrating use of fft (Fast Fourier Transform)
I posted the following Matlab script in response to a question on Signal Processing. Here is the questions with my answer.
I am looking for comments on how to make this code more instructive for the ...
0
votes
1answer
312 views
how I can change this multi-loop to reduce the computation time in Matlab
how I can change this multi-loop to reduce the computation time?
A is a matrix (5x10000) with the fifth line contains values between 1 and 50 corresponding to different events of an experiment. My ...
1
vote
1answer
170 views
Is there a way to reduce the computation time in this Matlab program?
Is there a way to reduce the computation time in this program that eliminates the columns of a matrix A if for a given column the element of line 4 is equal to the element in row 5:
...
1
vote
1answer
552 views
how to reduce the computation time for this program matlab?
I started this program for five hours and it has not yet completed. I wonder if we can make changes to reduce the computation time.
I use several for loop and this greatly increases the computation ...
3
votes
1answer
119 views
