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random: Add poisson-random-float.

db4
Doug Coleman 2012-12-07 09:29:48 -08:00
parent a46bcfe85c
commit ae276ec225
1 changed files with 6 additions and 0 deletions
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6
basis/random/random.factor
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@ -287,6 +287,12 @@ M: float random [ f ] [ 0.0 swap uniform-random-float ] if-zero ;
: power-random-float ( alpha -- n ) : power-random-float ( alpha -- n )
[ random-unit log e^ 1 swap - ] dip recip ^ ; [ random-unit log e^ 1 swap - ] dip recip ^ ;
! Box-Muller
: poisson-random-float ( mean -- n )
[ -1 0 ] dip
[ 2dup < ]
[ [ 1 + ] 2dip [ random-unit log neg + ] dip ] while 2drop ;
{ {
{ [ os windows? ] [ "random.windows" require ] } { [ os windows? ] [ "random.windows" require ] }
{ [ os unix? ] [ "random.unix" require ] } { [ os unix? ] [ "random.unix" require ] }