# MATLAB: Symbolic matrices optimization with fmincon

error while optimizing with fminconfminconmatricesoptimizationsymbolic variable optimization

I am trying to minimize a function. The function is , where and are defined as
``chi= rand(4,4) %% for examplesyms t [1 16] realtt=[t1 0 0 0;t5+1i*t6 t2 0 0;t11+1i*t12 t7+1i*t8 t3 0;t15+1i*t16 t13+1i*t14 t9+1i*t10 t4];tt2=[t1 0 0 0;t5-1i*t6 t2 0 0;t11-1i*t12 t7-1i*t8 t3 0;t15-1i*t16 t13-1i*t14 t9-1i*t10 t4];chi1=simplify(transpose(tt2)*tt) %% chi1 is 4x4 matrix with 16 symbolic variablesfun=sum((chi1-chi).^2);g=matlabFunction(fun);rng default;gs=GlobalSearch;opts=optimoptions(@fmincon,'Algorithm','interior-point');problem = createOptimProblem('fmincon','x0',[],'objective',g,'lb',[],'ub',[],'options',opts)t=run(gs,problem)``
and I am encountering an incessant error
``PROBLEM structure should have a non-empty X0 field.``
After putting arbitrary values of 'x0' (16 values), the error changes to
``not enough input arguments.``
Currently, not able to sort out where the problem is. Any help will be appreciated.

``chi= rand(4,4) %% for examplesyms t [1 16] realt = reshape(t,4,4); % You need this for the function to be well-definedtt=[t1 0 0 0;t5+1i*t6 t2 0 0;t11+1i*t12 t7+1i*t8 t3 0;t15+1i*t16 t13+1i*t14 t9+1i*t10 t4];tt2=[t1 0 0 0;t5-1i*t6 t2 0 0;t11-1i*t12 t7-1i*t8 t3 0;t15-1i*t16 t13-1i*t14 t9-1i*t10 t4];chi1=simplify(transpose(tt2)*tt) %% chi1 is 4x4 matrix with 16 symbolic variablesfun=real(sum((chi1-chi).^2,'all')); % I had to take the real part because fmincon needs real valuesg=matlabFunction(fun,'vars',{t}); % This is also necessary: fmincon takes just one input argumentrng default;gs=GlobalSearch;opts=optimoptions(@fmincon,'Algorithm','interior-point');problem = createOptimProblem('fmincon','x0',randn(4),'objective',g,'lb',[],'ub',[],'options',opts)t=run(gs,problem)``