constrained pso : how to set initial population ?

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genevois pierre 2016-12-30

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https://ww2.mathworks.cn/matlabcentral/answers/318586-constrained-pso-how-to-set-initial-population

评论： Walter Roberson 2017-2-21

采纳的回答： Walter Roberson

hi, i tried

options = optimoptions('particleswarm', 'InitialPopulation', tous_xi);

where tous_xi contains initial positions, and i get the error :

'InitialPopulation' is not an option for PARTICLESWARM.

Can you help me to set that initial population? Thank you

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genevois pierre 2017-1-3

编辑：Walter Roberson 2017-2-21

在 MATLAB Online 中打开

hi, i switched from my laptop (Matlab R2015b) to my office's PC (Matlab R2013a) : i will use Matlab R2013a from now on. Does this change in Matlab version changes something to your last message ?

The constraints can be satisfied, because i get no problem when i use ga instead of pso.

With Matlab R2013a, when i run

options_pso = psooptimset(@pso);
options_pso = psooptimset('InitialPopulation', tous_xi);
[x, fval, exitflag] = pso(@mapse_vu_sd, 7, [], [], [], [], ...
    lx, ux, @mapse_CNL_sd_c, options_pso)

the error is

Error using psocheckinitialpopulation (line 103)
Problem is infeasible due to nonlinear constraints
Error in pso (line 338)
    [state,options] = psocheckinitialpopulation(state,...
Error in essai_pso_matlab (line 40)
[x, fval, exitflag] = pso(@mapse_vu_sd, 7, [], [], [], [], ...

but since there is no error due to the 2 lines that use psooptimset, it seems to mean that 'InitialPopulation' is not a problem ... Thank you again for your help.

Walter Roberson 2017-1-3

pso() and psooptimset() are not Mathworks routines. They appear to be https://www.mathworks.com/matlabcentral/fileexchange/38224-co-blade-software-for-analysis-and-design-of-composite-blades or https://www.mathworks.com/matlabcentral/fileexchange/25986-constrained-particle-swarm-optimization

The Mathworks routine is particleswarm() introduced in R2014b, which does not support constraints.

Someone would have to study the constrained pso() code to determine why it does not feel that the constraints can be satisfied. I do not feel that is something I would have time to do.

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Answer 1

Walter Roberson 2016-12-30

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https://ww2.mathworks.cn/matlabcentral/answers/318586-constrained-pso-how-to-set-initial-population#answer_248964

InitialSwarmMatrix is the option

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Answer 2

jonas_h 2017-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/318586-constrained-pso-how-to-set-initial-population#answer_255696

编辑：Walter Roberson 2017-2-21

在 MATLAB Online 中打开

Did you find a solution yet? I have the same problem. I am also using this PSO https://de.mathworks.com/matlabcentral/fileexchange/25986-constrained-particle-swarm-optimization because I need the nonlinear constraints.

I get the same error and thought I made a mistake but with ga everything is working fine (much slower but at least it is working). I tried the pso several times and sometimes it is working (maybe in 2/10 cases) In the other cases there is this error:

Error using psocheckinitialpopulation (line 103)
Problem is infeasible due to nonlinear constraints
Error in pso (line 338)
    [state,options] = psocheckinitialpopulation(state,...

There are possibilieties where there constraints can be satiefies. Otherwise it would not be working in some cases.

After this I tried to set the initialpopulation:

psooptimset(...InitialPopulation',startwerte);

"startwerte" should be a vector of my starting values (the function contains 12 variables which should be optimized). With the starting values the constraints are 100% satisfied. This did not help very much. maybe it is working more often now but not everytime.

Is this a bug in the PSO? I think then I have to use the ga. I would like to use the PSO because it is much faster in my case.

Thanks!