MATLAB: Does the solutions of nonlinear system are not correctly computed

fsolve

I hv the following system of nonlinear equations for computing switching angles of a multilevel inverter, taken as an example from my pwr elctnx book
function F = test(x)
F=[cos(5*x(1)) + cos(5*x(2))+cos(5*x(3)) + cos(5*x(4))+ cos(5*x(5))  
    cos(7*x(1)) + cos(7*x(2))+cos(7*x(3)) + cos(7*x(4)) + cos(7*x(5))
    cos(11*x(1)) + cos(11*x(2))+cos(11*x(3)) + cos(11*x(4))+cos(11*x(5))
    cos(13*x(1)) + cos(13*x(2))+cos(13*x(3)) + cos(13*x(4))+ cos(13*x(5))
    cos(x(1)) + cos(x(2))+cos(x(3)) + cos(x(4))+ cos(x(5))-4];
I have used the matlab function FSOLVE with OPTIMSET to sovle this system for x1,x2,x3,x4 and x5 and on ocassions hv increased parameters like 'MaxFunEval' and MaxIter but the matlab answers are different from those given in the book ie x1=6.57;x2=18.94;x3=27.18;x4=45.15;x5=62.24;(in Degrees). plzzz anybody help me with this. I need it urgently

Best Answer

It looks like there must exist a solution with all x(1)=x(2)=x(3)=x(4)=x(5), due to the symmetry of your F. Therefore, the solution in your book is either just one of many, or you have incorrectly implemented your F(x). What is the final value of F(x) that fsolve returns?
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