# function with two variables

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ali akbar on 1 May 2020
Answered: Walter Roberson on 2 May 2020
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.

Ameer Hamza on 1 May 2020
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.
##### 2 CommentsShowHide 1 older comment
Ameer Hamza on 2 May 2020
I am glad to be of help.

Walter Roberson on 2 May 2020
Change
g = matlabfunction(realG1)
to
g = matlabfunction(realG1, 'vars', {[theta, xi]});
Now you do not need to modify your objective function.