clear all;
[x,y]  = meshgrid(-1.5:0.06:1.5);
    r  = sqrt(x.^2+y.^2);
theta  = atan2(y,x);
    n  = 3;
alphan = 6.3802;

B   = besselj(n,alphan*r);
Psi = B.*exp(n*i*theta);
U   = real(Psi);

surf(x,y,U);
% imagesc(U);
% contour(x,y,U,10);
