Thanks a lot for your advice. Now I've imported a black/white photo of a the diffraction pattern from a circular aperture and I want to make a 3D-graph that represent the intensity of the pattern. I've saved the photo as "airyimg" in maple.
My first idea was to use the command "pointplot3d" to make the graph, so I've made the following sequence to calculate the intensity to every pixel:
[seq](seq([j, n, airyimg(j, n)], n = 1 .. 200), j = 1 .. 200)
For some reasons this sequence only gives a small part of the entire picture. In fact I've found out that;
sometimes returns values for negative integers. And the setup:
> l1 := ([seq])(seq([j, n, airyimg(j, n)], n = -600 .. -1), j = -200 .. -1);
> l2 := ([seq])(seq([j, n, airyimg(j, n)], n = 1 .. 600), j = 1 .. 200);
> l3 := [l1, l2];
> pointplot3d(%, axes = boxed);
gives two strange-scaled diffraction patterns in the same plot.
Hope you can help me.