How to get fsolve return number of iterations

Hi all,

Yet another fsolve question. I am trying to compare now various root finding functions I have as well as fsolve.

In the help file it shows this;

[x,fval,exitflag,output] = fsolve(fun,x0,options)

and this

output.funcCount

so I would like to have this;

[root,output]  = fsolve(myfun,x0,options);
count = output.iterations

i receive this;

Struct contents reference from a non-struct array object.

Error in zerotest (line 57)
    output.iterations

What I am missing?

Thanks a lot.

Answer 1

[ttopal]

Okay. So it turns out it needs this;

   [x,fval,exitflag,output] = fsolve(fun,x0,options)
   output.iterations

you have to return fval and exitflag even if you dont use them.

[Stephen23]

"you have to return fval and exitflag even if you dont use them."

It is not necessary to allocate outputs if you do not want them:

 [x,~,~,out] = fsolve(...);
 out.iterations

https://www.mathworks.com/help/matlab/matlab_prog/ignore-function-outputs.html

[ttopal]

Thanks Stephen,

I did not know that either.