function [ y ] = f_stmod( x )
%F_STYBLINSKI_TANG modified

n = length(x);
y = 0;
M = triu((n+1)*ones(n)-kron(1:n,ones(n,1)));
M = M+eye(n);
x = M*x;
for i = 1:n
   y = y+x(i)^4-16*x(i)^2+35*x(i); 
end
y=y+n*171.19854821721323;


end

