How can I use fminsearch with forloop in the Matlab?-CodePudding

I want to find the local minimum of the function using loop.

Basically, the function has 2 choice variables say f(x,y).

But I want to find the minimum of f(x,y) with y values starting from 1,2,3...10 using for loop.

For example,

obj = @(x,y) x^2   x*y   y^2
for i = 1:30
    fminsearch(...)
end

but I am not sure how to use it correctly.

Can anyone help me with this issue?

Thanks in advance.

CodePudding user response：

You can use a wrapper function:

obj = @(x,y) x^2   x*y   y^2;
for i = 1:30
    y_i = generate_ith_y_value(i);
    fminsearch(@(x) obj(x,y_i), x0)
end

If you want to find the pair (x,y) so that obj(x,y) is a local minimum rather than finding the local minimum when y is a fixed value (like what you tried to do with for loop), then it's better to combine x and y into a single vector.

You can modify obj directly:

% x(1) = x, x(2) = y
obj = @(x) x(1)^2   x(1)*x(2)   x(2)^2;
fminsearch(@(x) obj(x), [x0; y0])

If you can't modify obj directly, use a wrapper function that takes one input parameter and seperates it:

obj = @(x,y) x^2   x*y   y^2;

% xx(1) = x, xx(2) = y
fminsearch(@(xx) obj(xx(1),xx(2)), [x0; y0])