Show an expression on each iteration of the optimization

Hello,

I'm using "lsqnonlin" to optimize a function and would like to show a expression, important for my problem, in each iteration. This expression depends on the optimization variables, therefore will change with each iteration. I understand that I can do this with OutputFcn, but I failed to understand how. I think it should not be complicated, please help!

The indicator is: (z(1)*z(2)+6)/z(4)+z(5)*z(6)

Thanks in advance!

Answer 1

[Alan Weiss]

Write a function named Jurgenoutput consisting of the following:

 function stop = Jurgenoutput(z,optimValues,state)
 stop = false;
 indicator = (z(1)*z(2)+6)/z(4)+z(5)*z(6);
 disp(indicator)

Include the output function in your solver call as follows:

 options = optimoptions('lsqnonlin','OutputFcn',@Jurgenoutput);
 x = lsqnonlin(fun,x0,lb,ub,options)

Alan Weiss

MATLAB mathematical toolbox documentation

[Jurgen]

Thanks! but, could I use a function defined outside the function Jurgenoutput? I'm trying with the following, but apparently does not recognize the external function

 function stop = Jurgenoutput(z,optimValues,state)

   stop = false;

   indicador=double(g2c(z(1),z(3),z(2)))

   disp(indicador)

[Matt J]

If g2c() is s on your MATLAB path, there's no clear reason it wouldn't have been recognized.

[Jurgen]

Apparently I can not use any variable defined outside the output function, I want to do the following and can not.

 function stop = Jurgenoutput(z,optimValues,state)
 stop = false;
 indicator = (z(1)*z(2)+6)/z(4)+z(5)*z(6)*g1c;
 disp(indicator)

where g1c was defined outside Jurgenoutput and is a constant number.

[Alan Weiss]

You need to look at how to pass extra parameters. Probably, a nested function would pass g1c successfully.

Alan Weiss

MATLAB mathematical toolbox documentation