Date: Dec 16, 2011 6:10 PM
Author: Marcio Barbalho
Subject: fsolve won't solve non-linear system of equations

Hi you all.

I've had a hard time understanding why matlab can't solve this problem using fsolve.

It's a system of non-linear equations.

These are the m-files:

function F = ORVP(k)
F(1) = 0.6*k(3)/k(2)*44.44-k(1);
F(2) = 1/( 0.6/(k(2)*44.44)+0.4/(k(4)*65.43))-k(3);
F(3) = 1 - k(1)-k(5);
F(4) = exp(1.107*k(5)^2)-k(2);
F(5) = exp(1.107*k(1)^2)-k(4);

k0 = [0.81; 1.03; 62.89; 2.09; 0.19];
[x,fval] = fsolve(@ORVP,k0,options)

where k0, starting guess, is the solution already. It just won't get to the result. I've double-checked the equations, they are fine!

Any ideas?

Many thanks