For LSSolve I have the objective function as a procedure that calls another procedure (procPatientres) according to below:

p:=proc(x::Vector, y::Vector)

y[1]:=procPatientres("patient specific parameters", x[1],x[2]);

y[2]:=procPatientres("patient specific parameters", x[1],x[2]);

end proc;

This is a test example where I only fit to patients. Since the returned residuals, y[1] and y[2], are just values the first derivative is simple zero and I...