function [X, f1] = DeJong4(Xi)
n = 30;
b = 1:30;
a = randn(1,n);
LL = -1.28;              %Lower limit
UL = 1.28;               %Upper limit
X = LL + rand(1,n)*(UL-LL);% step1 Choose starting design X, 
f1 = sum((X.^4).*b + a);
end