% This is the function invoked by the code  hw2_EX_main.m

function f=fun4_hw3_starting_method(x,y);

global a              % The meaning of this line is explained in the main code.

% f = sqrt(y);
% f = a*x.*(1+y.^2);
% f=a*x.*(1+cos(2*y));
% f = a*x.^3*(1+y.^2);
f = 2*y + 5*exp(3*x);