Abelian sandpile model: Difference between revisions
add RPL
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Passing in a stack size of 20000 results in: [https://github.com/thundergnat/rc/blob/master/img/Abelian-sandpile-sdl2.png Abelian-sandpile-sdl2.png] (offsite .png image)
=={{header|RPL}}==
Using the built-in matrix data structure fulfils the requirements of the task:
[[1 2 0][2 1 1][0 1 3]] [[2 1 3][1 0 1][0 1 0]] +
'''Output:'''
1: [[3 3 3]
[3 1 2]
[0 2 3]]
{| class="wikitable" ≪
! RPL code
! Comment
|-
|
≪ ROT OVER RE + { } + ROT ROT IM + +
≫ ‘<span style="color:blue">→IDX</span>’ STO
≪ DUP SIZE 1 GET → n
≪ '''DO'''
1 CF 1 n '''FOR''' h 1 n '''FOR''' j
'''IF''' DUP h j 2 →LIST GET 3 > '''THEN'''
1 SF DUP 0 CON
h j 2 →LIST -4 PUT
1 4 '''FOR''' a
h j (0,1) a ^ <span style="color:blue">→IDX</span>
'''IFERR''' 1 PUT '''THEN''' DROP2 '''END'''
'''NEXT''' +
'''END NEXT NEXT'''
'''UNTIL''' 1 FC? '''END'''
≫ ≫ ‘<span style="color:blue">SPILE</span>’ STO
|
<span style="color:blue">→IDX</span> ''( a b (c,d) → { a+c b+d } ) ''
<span style="color:blue">SPILE</span> ''( [[a]] → [[a]] ) ''
loop
for h, j = 1 to n
if a[h,j] > 3 then
set flag, create empty matrix b
b[h,j] = -4
for a = 1 to 4
(x,y) = (h,j) + i^a
b[x,y] = 1 only if x > 0 and y > 0
a += b
end if, next h, j
until all elements <= 3
return a
|}
It is sometimes necessary to run the program several times to reach stability: user's eye is much faster than a program to detect a remaining unstable sandpile. This is the way in RPL.
It may nevertheless make sense when working on large matrices to have to run the program only once. In this case, the addtional line below shall be inserted after the <code>END NEXT NEXT</code> line:
1 n '''FOR''' h 1 n '''FOR''' j '''IF''' DUP h j 2 →LIST GET 3 > '''THEN''' 1 SF '''END NEXT NEXT'''
{3 3} 3 CON '<span style="color:green">S3</span>' STO
[[2 1 2][1 0 1][2 1 2]] '<span style="color:green">S3ID</span>' STO
<span style="color:green">S3</span> <span style="color:green">S3ID</span> + <span style="color:blue">SPILE</span> <span style="color:blue">SPILE</span>
<span style="color:green">S3ID</span> DUP + <span style="color:blue">SPILE</span> <span style="color:blue">SPILE</span>
{{out}}
<pre>
2: [[ 3 3 3 ]
[ 3 3 3 ]
[ 3 3 3 ]]
1: [[ 2 1 2 ]
[ 1 0 1 ]
[ 2 1 2 ]]
</pre>
=={{header|Rust}}==
Line 3,449 ⟶ 3,513:
</pre>
=={{header|Scheme}}==
{{works with|Chez Scheme}}
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