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Implement the Abelian sandpile model also known as Bak–Tang–Wiesenfeld model. Its history, mathematical definition and properties can be found under its wikipedia article.

The task requires the creation of a 2D grid of arbitrary size on which "piles of sand" can be placed. Any "pile" that has 4 or more sand particles on it collapses, resulting in four particles being subtracted from the pile and distributed among its neighbors.

It is recommended to display the output in some kind of image format, as terminal emulators are usually too small to display images larger than a few dozen characters tall. As an example of how to accomplish this, see the Bitmap/Write a PPM file task.

Examples up to 2^30, wow!
javascript running on web
Examples:

0 0 0 0 0    0 0 0 0 0
0 0 0 0 0    0 0 1 0 0
0 0 4 0 0 -> 0 1 0 1 0
0 0 0 0 0    0 0 1 0 0
0 0 0 0 0    0 0 0 0 0

0 0 0 0 0    0 0 0 0 0
0 0 0 0 0    0 0 1 0 0
0 0 6 0 0 -> 0 1 2 1 0
0 0 0 0 0    0 0 1 0 0
0 0 0 0 0    0 0 0 0 0

0  0 0  0  0    0 0 1 0 0
0  0 0  0  0    0 2 1 2 0
0  0 16 0  0 -> 1 1 0 1 1
0  0 0  0  0    0 2 1 2 0
0  0 0  0  0    0 0 1 0 0

grid=: 4 : 'x (<<.-:2$y)} (2$y)$0'         NB. y by y grid with x grains in middle
ab=: - [: +/@(-"2 ((,-)=/~i.2)|.!.0]) 3&<  NB. abelian sand pile for grid graph
require 'viewmat'                          NB. viewmat utility
viewmat ab ^: _ (1024 grid 25)             NB. visual 