% Example of nonlinear system resolution: 
%   g(1)=x(1)-4*x(1)*x(1)-x(1)*x(2);
%   g(2)=2*x(2)-x(2)*x(2)+3*x(1)*x(2);
% that can be solved by way of example via the Matlab 
% command "fsolve" that uses the quasi-Newton method.
% The initial conditions are given in the vector x0.

x0=[1 1]';
x=fsolve(@nonlineareq,x0)