MATLAB: How do you use fsolve to solve simultaneous equations

Question

Hello,

I am new to Matlab and would like to learn how to use fsolve to solve simultaneous equations.

Say you have the following equations:

x+y+z=2

y^2=z+5

x+z^3=2

Zero degrees of freedom, how do you solve for x, y and z using fsolve?

Thank you very much,

M

Answer 1

You need to rewrite as F(X)=0 where X is your vector of unknowns

 fun=@(X) [sum(X)-2; X(2)^2 -X(3)-5 ; X(1)+X(3)^3-2];

Then

x = fsolve(fun,x0)

where x0 is your initial guess. There are other input/output arguments that you can use to refine the behavior of FSOLVE (see "doc fsolve").