How to minimize a nonlinear function?

Hi everyone, I heve tried to solve a nonlinear equation in matlab where x0 = [0;1;2] is the initial value for search

So I wrote a function :

function f = myfun(x)

f = (1./(1+(x1-x2).^2)) + sin.*(0.5*pi.*x2.*x3) + exp(((-x1+x)./x2)-2).^2)

end

Then:

x1 = 0; x2 = 1; x3 = 2; x0 = [x1;x2;x3];

options = optimoptions('fsolve','Display','iter');

[x,fval] = fsolve(@myfun,x0,options)

... But the following error appears:

"Caused by:

Failure in initial objective function evaluation. FSOLVE cannot continue."

How can i fix that.

I thank you.

Answer 1

[Ameer Hamza]

There are issues with the definition of 'myfun'. Compare it with the following to see the errors.

function f = myfun(x)
x1 = x(1);
x2 = x(2);
x3 = x(3);
f = (1./(1+(x1-x2).^2)) + sin(0.5*pi.*x2.*x3) + exp(((-x1+x)./x2)-2).^2;
end

Answer 2

[Star Strider]

It took a bit to correct the parentheses problems in ‘myfun’.

With that solved:

myfun = @(x1,x2,x3) (1./(1+(x1-x2).^2)) + sin(0.5*pi.*x2.*x3) + exp((-(x1+x3)./x2-2).^2);

options = optimoptions('fsolve','Display','iter')
x1 = 0; x2 = 1; x3 = 2; x0 = [x1;x2;x3];
[x,fval] = fsolve(@(p)myfun(p(1),p(2),p(3)),x0,options)

produces:

x =
  -0.823049966296178
   1.775543504609500
   1.177574125107562

fval =
     1.262730886088113e+02

.

.