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Simple example of PSO algorithm

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Simple example of PSO algorithm


Andrea Cirillo


Matlab function to find the minimum of a objective function with the PSO Algorithm

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It finds the minimum of a n variables function with the Particle Swarm Optimization Algorithm.

% The input parameters are:
% -func: it's the objective function's handle to minimize
% -numInd: it's the number of the swarm's elements
% -range: it's the range in which the elements must be created
% -n_var: it's the number of function's variables
% -tolerance: it's the tolerance for the stop criterion on the swarm's
% radius
% -numIter: it's the max iterations' number
% -pesoStoc: it's the swarm's movability
% The output parameters are:
% -p_min: the minimum point find
% -f_min: the minimum value of the function
% -iter: the number of iterations processed

MATLAB release MATLAB 7.11 (R2010b)
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Comments and Ratings (11)
20 Jul 2014 Sajeev J

Sajeev J

Hi Andrea, I am doing a classification problem. I am classifying a protein as either cancerous or not with 644 features. My guide instructed me to optimize the feature vector using PSO. I am clear with your code, but I don't know how to write the objective function. My SVM classifier works well with 644 features and put in two groups (1 or 0). Hope you can help me. Thanks

17 Apr 2013 sangjinlee


12 May 2012 Andrea Cirillo

Andrea Cirillo

Of course the error is on the input variables that you use for PSO function. You can follow the simple example of the previous comment.

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12 May 2012 KT


hi!!!! i am trying to understand the concept of PSO but the code is giving me the following error:
??? Index exceeds matrix dimensions.

can some one please tell where i am wrong???

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15 Mar 2012 SANI LAWAL


Hello Michael, it do run but u need to define the range and other input parameters as given by Mr Andrea, it runs perfectly,but my only doubt is the minimal value because i got 1.0e+006,so i want be sure is it the minimum value?
Thank you so much

08 Mar 2012 Michael Bernard

Michael Bernard

Why does the example fail to run in matlab? I got this message when I ran the file.The message reads :"??? Input argument "range" is undefined.
Error in ==> pso at 19
range_min=range(1); % Range for initial swarm's elements "

I have never used partical swarm.Am new to it

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19 Dec 2011 Giacomo


It works fine!!!

13 Dec 2011 Akbar


I am trying to solve Skew correction problem with PSO. I have a prob with defining the objective function.

This is a simple example given above. The problem I am facing is that I have to maximize the difference of maxima and minima of the projection profile of the image. Given as,


theta here is swarm particle (1D)

How should i be using this 'theta' in my function to maximize the objective function given as above.


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14 Nov 2011 Ahmet Ahmet

Ahmet Ahmet

24 Oct 2011 Andrea Cirillo

Andrea Cirillo

The objective function have to be a matlab function (you can create a .m function) with its input and output parameters. After you created the function, you can obtain the function handler with the @ symbol. A simple example: if c = sum(a) is my function, I will create the follow matlab function.

function c=sum(a)

where 'a' is a vector that contain the input parameters. After I can define the function handle:
f_vett=@(x) sum(x)
where f_vett is a multivariable function and x is the vector that contains the variables of the function.

Now, if f_vett is a objective function, you can use the pso algorithm as follow:

[p_min, f_min, iter]=pso(f_vett, 5000, [0 20], 10, 0.0001, 200, 0.7)

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24 Oct 2011 Ahmed Hany

Ahmed Hany

Hello Andrea ;

Pleass tell me the format used for input func ( objective function ) .

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