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Cleanup of math.analysis

db4
Aaron Schaefer 2008-11-06 01:20:08 -05:00
parent c9449cf3f5
commit 636c344eb0
1 changed files with 17 additions and 17 deletions
extra/math/analysis

34
extra/math/analysis/analysis.factor
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@ -1,7 +1,7 @@
! Copyright (C) 2008 Doug Coleman, Slava Pestov.
! Copyright (C) 2008 Doug Coleman, Slava Pestov, Aaron Schaefer.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel math math.constants math.functions math.intervals
math.vectors namespaces sequences combinators.short-circuit ;
USING: combinators.short-circuit kernel math math.constants math.functions
math.vectors sequences ;
IN: math.analysis
<PRIVATE
@ -14,7 +14,7 @@ IN: math.analysis
: gamma-p6
{
2.50662827563479526904 225.525584619175212544 -268.295973841304927459
80.9030806934622512966 -5.00757863970517583837 0.0114684895434781459556
80.9030806934622512966 -5.00757863970517583837 0.0114684895434781459556
} ; inline
: gamma-z ( x n -- seq )
@ -22,16 +22,16 @@ IN: math.analysis
: (gamma-lanczos6) ( x -- log[gamma[x+1]] )
#! log(gamma(x+1)
[ 0.5 + dup gamma-g6 + dup [ log * ] dip - ]
[ 0.5 + dup gamma-g6 + [ log * ] keep - ]
[ 6 gamma-z gamma-p6 v. log ] bi + ;
: gamma-lanczos6 ( x -- gamma[x] )
#! gamma(x) = gamma(x+1) / x
dup (gamma-lanczos6) exp swap / ;
[ (gamma-lanczos6) exp ] keep / ;
: gammaln-lanczos6 ( x -- gammaln[x] )
#! log(gamma(x)) = log(gamma(x+1)) - log(x)
dup (gamma-lanczos6) swap log - ;
[ (gamma-lanczos6) ] keep log - ;
: gamma-neg ( gamma[abs[x]] x -- gamma[x] )
dup pi * sin * * pi neg swap / ; inline
@ -42,22 +42,22 @@ PRIVATE>
#! gamma(x) = integral 0..inf [ t^(x-1) exp(-t) ] dt
#! gamma(n+1) = n! for n > 0
dup { [ 0.0 <= ] [ 1.0 mod zero? ] } 1&& [
drop 1./0.
] [
dup abs gamma-lanczos6 swap dup 0 > [ drop ] [ gamma-neg ] if
drop 1./0.
] [
[ abs gamma-lanczos6 ] keep dup 0 > [ drop ] [ gamma-neg ] if
] if ;
: gammaln ( x -- gamma[x] )
#! gammaln(x) is an alternative when gamma(x)'s range
#! varies too widely
dup 0 < [
drop 1./0.
] [
dup abs gammaln-lanczos6 swap dup 0 > [ drop ] [ gamma-neg ] if
drop 1./0.
] [
[ abs gammaln-lanczos6 ] keep dup 0 > [ drop ] [ gamma-neg ] if
] if ;
: nth-root ( n x -- y )
[ recip ] dip swap ^ ;
swap recip ^ ;
! Forth Scientific Library Algorithm #1
!
@ -116,6 +116,6 @@ PRIVATE>
: stirling-fact ( n -- fact )
[ pi 2 * * sqrt ]
[ dup e / swap ^ ]
[ 12 * recip 1 + ]
tri * * ;
[ [ e / ] keep ^ ]
[ 12 * recip 1+ ] tri * * ;