MATLAB: Help with optimization tool

gamultiobjective genetic algorithmoptimization

Hello,

I am new to MATLAB and I am using Optimization tool in MATLAB for a research project. when i try to optimize the following function 
function y = test2()
y=zeros(1:4);
f=funVAMPzero(x);
a=f.a;
y(1)= (a(1));    
y(2)=(a(2));
y(3)=(a(3));
y(4)=(a(4));
end

i get an error message saying too many input arguments. I have used f=funVAMPzero(x) to get variable from another m-file whose values i have to optimze.

Inputs on the issue would be very helpful. Thanks in advance!!

Best Answer

The error is occuring because the optim tool is trying to call test2() with a vector input, but you do not declare a vector input in the function's declaration. The interface to the objective function should look like

function y = test2(x)

where x is a vector of your design variables.

Futhermore, the output of the objective function depends on your problem. What solver are you using? (It's an option specified in the optimtool GUI.) Can you describe your goal (objective function and constraints)in a bit more detail?

Related Solutions

MATLAB: Dominated points are displayed in Pareto front – after termination

Thank you for supplying your code. Your objective function values are generated by random numbers. Every time they are evaluated, they yield different values. This violates the assumption that an objective function be reproducible, meaning evaluating it for the same inputs yields the same output.

I would not expect that any of our optimization or multiobjective optimization functions would give reasonable output.

I also do not see how you called gamultiobj with your objective function. Generally, an objective function should take one input, usually called x. However, your objective function takes many inputs. So I suspect that there might be an error, but without seeing your gamultiobj call, I cannot be certain.

Finally, you have a load statement in your objective function. Don't do that, it leads to very poor performance, Instead, load the variables into your workspace once, then pass their values using anonymous functions or nested functions.

Alan Weiss

MATLAB mathematical toolbox documentation

MATLAB: Symbolic maths and optimization

Your first problem is the use of numbered variables. That is the worst mistake that new coders make. INSTEAD, USE VECTORS. USE MATRICES.

So you might have a for loop, with ind as a variable, where we might see lines like this:

for ind = 1:numfarms
   xR(ind) = X(84+ind)*X(104 + ind);
   ...
end

There still is absolutely no need for symbolic here. Just a need to learn to use vectors, and to learn how to use an objective function for fmincon.

Even better than using a loop, you need to start learning how to use MATLAB as it is designed to be used. So in one line, we can do this:

xR = X(85:104).*X(105:124);

Everything I said in my comment is still true. When you know only one way to write code, you use it, for everything. Every problem looks like a nail when you have only a hammer in your toolbox. So you know how to use syms. And since you think you don't know what those variables are, then you think you need to use symbolic variables. Then you learned how to created numbered symbolic variables, like X86, X87, etc.

This path will lead you into programming hell. It is a place you don't want to live in (it gets really hot in programming hell, I think they have poor air conditioning), but you don't need to go there. What you will find is all those numbered variables will create bugs in your code. All you need to do is mistype one line and you will never find the bug. And as you have found, wanting to type all those lines for every variable you need to create is programmatically abhorrent.

So instead, work with vectors. An optimization tool looks at your objective as a black box. It passes in a guess at the unknowns to your objective. Then you can unpack that vector of unknowns, computing the various parts of your objective.

xR = X(85:104).*X(105:124);
avg_xR = [sum(xR(1:19)), sum(xR(2:20))]/10;
...

Still, no need for anything symbolic. And certainly no need for a long list of numbered variables. Learn to use MATLAB as a language of matrices, vectors, etc. Even the name MATLAB invokes the phrase "MATrix LABoratory", as it should.

Best Answer

Related Solutions

MATLAB: Dominated points are displayed in Pareto front – after termination

MATLAB: Symbolic maths and optimization

Related Question