function with two variables

I have a long symbolic function which is evaluated inside matlab and contains two variables theta and xi.

realG1=((1.0*(cos(theta) - sin(theta)*sin(xi)*1.0*i)*(cos(theta)*(0.008866522 - 0.02124593*i) + 0.00765004*cos(xi)*sin(theta) + sin(theta)*sin(xi)*(- 0.02124593 - 0.008866522*i)) - cos(xi)*sin(theta)*(0.06971876*cos(theta) + cos(xi)*sin(theta)*(0.008866522 + 0.02124593*i) - sin(theta)*sin(xi)*0.06971876*i) + 0.03551045 + 0.008096911*i)^2 )

My code is following

g= matlabfunction(realG1)
 rng default
gs=GlobalSearch;
opts = optimoptions(@fmincon,'Algorithm','interior-point');
problem = createOptimProblem('fmincon','x0',[0,0],'objective',g,'lb',[0,0],'ub',[],'options',opts);
[theta,xi,output] = run(gs,problem)

when I run it for only theta(removing xi on the last line), it minimizes just fine. But with two variables, it says not ''Not enough input arguments''. Can anyone help.

Answer 1

[Ameer Hamza]

Change the code like this

g = matlabfunction(realG1)
obj_fun = @(x) g(x(1),x(2)); %<<=== add this line
rng default
gs=GlobalSearch;
opts = optimoptions(@fmincon,'Algorithm','interior-point');
problem = createOptimProblem('fmincon','x0',[0,0],'objective',obj_fun,'lb',[0,0],'ub',[],'options',opts);
[theta,xi,output] = run(gs,problem)                          % ^ change to obj_fun

fmincon only accepts a function handle with input if your function has two inputs, the use 'x' as a vector with two elements.

[ali akbar]

Thank you ameer. You're a life saviour.

Best

[Ameer Hamza]

I am glad to be of help.

Answer 2

[Walter Roberson]

Change

g = matlabfunction(realG1)

to

g = matlabfunction(realG1, 'vars', {[theta, xi]});

Now you do not need to modify your objective function.