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Talk:Generate Chess960 starting position: Difference between revisions
Talk:Generate Chess960 starting position (view source)
Revision as of 01:55, 13 May 2014
, 10 years ago→random starting position: added the REXX source that produced the histogram.
(→random starting position: ruby code was biased too) |
(→random starting position: added the REXX source that produced the histogram.) |
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file 8=270847 ============================================================
</pre>
The REXX program to produce the histograhs (shown above) is:
<lang rexx>/*REXX program generates a histogram of 100,000 rook placement positions*/
parse arg seed times . /*obtain optional args from C.L. */
if times=='' then times=100000 /*use default for TIMES? {100k} */
if seed\=='' then call random ,,seed /*if SEED specified, use the seed*/
rooks.=0 /*zero the rook position counters*/
do t=1 for times /*════════════════════════════════════════════════════*/
r1=random(1 ,8); /*place the first rook on rank1.*/
r1m=r1-1; r1p=r1+1 /*used for faster comparisons. */
do forever; r2=random(1,8) /*place the second rook on rank1.*/
if r2==r1 then iterate /*position is the same as rook1. */
if r2==r1m then iterate /*it's immediately before rook1. */
if r2==r1p then iterate /* " " after " */
leave /*found a good 2nd rook placement*/
end /*forever*/
rooks.r1=rooks.r1+1 /*bump rook (r1) position counter*/
rooks.r2=rooks.r2+1 /* " " (r2) " " */
end /*t ══════════════════════════════════════════════════════════════*/
mx=0; do j=1 for 8; mx=max(mx,rooks.j); end /*find max histo value*/
do k=1 for 8 /*display the eight files numbers*/
say 'file' k"="rooks.k copies('=', 60 * rooks.k % mx)
end /*k*/ /* [↑] display a nice histogram.*/
/*stick a fork in it, we're done.*/</lang>
Many thanks to (user) Steenslag for pointing out the un-randomness of the rook placement in the REXX code.
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