How to plot rastrigin function in matlab

I'm trying to plot rastrigin function this way

clear; clc; close all;
limits = repmat([-5 5], 2, 1);
[X,Y] = meshgrid(linspace(limits(1,1),limits(1,2),100),...
                   linspace(limits(2,1),limits(2,2),100));
Z = reshape(rastrigin([X(:)'; Y(:)']), 100, 100);
surf(X,Y,Z);
axis([-5 5 -5 5 0 90]);
shading interp

rastrigin.m

function [y] = rastrigin(x)
    d = length(x);
    sq = x.^2;   
    y = 10*d + sum(sq - 10*cos(2*pi*x));
end

But I'm getting empty figure

[Mahmoud ABURUB]

Rastrigin's Function has only one global minima at point [0,0]

the coden for ploting the function in 3D (X,Y,Z) is:

function [y]=rastringis(x1,x2)

dx1=length(x1);

dx2=length(x2);

for i=1:dx1

for j=1:dx2

y(i,j)=(20+x1(i).^2+x2(j).^2)-10*(cos(2*pi*x1(i))+cos(2*pi*x2(j)));

end

end

end

x1=[-5:0.1:5];

x2=[-5:0.1:5];

y=rastringis(x1,x2)

meshc(x1,x2,y);

the figure is attached to this message.

Answer 1

[dpb]

Your scaling seems to be out of whack--adding 10+length(x) is creating a Z of

>> [min(Z(:)) max(Z(:))]
ans =
 1.0e+03 *
  0.9810    1.0604
>>

Hence your axis command puts the Z axis range quite a long distance below where the data values are.

It appears from the functional definition, the offset factor you're looking for would be 20; 2X the scale factor of the cosine term. If I do that and then

zlim([0 90])

get an interesting figure, indeed. Hadn't heard of the rastrigin function...

[Atinesh Singh]

I didn't get you

[dpb]

Did you look at min/max of your Z array???? Apparently not...

Try removing the axis command entirely and see what happens. The combination of those should result in enlightenment.

Answer 2

[PRIYANSHI]

click on step button till you see a figure (till 6-7 line ) u will get the figure