Simple example of PSO algorithm

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

Description

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 (2010b)

[Ahmed Hany]

Hello Andrea ;

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

[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)
c=a(1)+a(2);

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)

[Ahmet Ahmet]

 

[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,

F(theta)=PP(maxima)-PP(minima);

theta here is swarm particle (1D)

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

Thanks

[Giacomo]

It works fine!!!

[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

[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

[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???

[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.