%This function models the second and other Eigen vector of Covariance matrices.
%Input: alpha = 4x1 vector with the four parameters
%     :     x = point at which to calculate FitU2
%Output:    U2(x)
function U2 = FitU2(b,x)

alpha = b(1);
beta = b(2);
gamma = b(3);
delta = b(4);

U2 = alpha*sin(beta*x.^(gamma)).*x.^(delta);