Use MATLAB® fminsearch function
Use the fminsearch function to determine the location of the maximum power density in several of the cases evaluated above. Compare the positions of the maxima predicted with fminsearch to those found graphically. Note that searching for a maximum is the negative of searching for a minimum and that fminsearch will find a local minimum so beware of the starting point for the search.
The syntax for the fminsearch is shown below where WGpower is a function that receives the vector input [0.01 0.01] corresponding to the x and y starting positions. The output xy corresponds to the vector values at the minimum and fmin is the value at the minimum.
[xy, fmin]=fminsearch(@WGpower,[0.01 0.01])
P(_,_)=((sin(m*pi*x/a)).^2.*(cos(n*pi*y/b)).^2)+((cos(m*pi*x/a)).^2.*(sin(n*pi*y/b)).^2)