function [f,g] = fg4(n,x)
%FG4 function and gradient for f4.CMSC 764 HW1.
%   [f,g] = fg4(n,x) gives the function value f and 
%   gradient g for the vector x of dimension n for 
%   test problem f4.
%
%   See also Hf4.

%  Geping Liu 09-21-06

f = (x(1,:) + x(2,:)) .^4 + x(2,:) .^2;
g = [4 .* (x(1,:) + x(2,:)) .^3; 
     4 .* (x(1,:) + x(2,:)) .^3 + 2 .* x(2,:)];