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Use s> and >s instead of r> and >r to avoid confusion

db4
Samuel Tardieu 2007-12-27 15:17:21 +01:00
parent 76c76b81ed
commit 3662ed8f0b
1 changed files with 9 additions and 6 deletions
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extra/math/algebra/algebra.factor
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@ -1,27 +1,30 @@
! Copyright (c) 2007 Samuel Tardieu
! See http://factorcode.org/license.txt for BSD license.
USING: kernel math math.ranges namespaces sequences vars math.algebra ;
USING: kernel math math.ranges namespaces sequences vars ;
IN: math.algebra
<PRIVATE
VARS: r-1 u-1 v-1 r u v ;
! The traditional name for the first variable is "r", but we want to avoid
! a redefinition of "r>" and ">r", so we chose to use "s" instead.
VARS: s-1 u-1 v-1 s u v ;
: init ( a b -- )
>r >r-1 0 >u 1 >u-1 1 >v 0 >v-1 ;
>s >s-1 0 >u 1 >u-1 1 >v 0 >v-1 ;
: advance ( r u v -- )
v> >v-1 >v u> >u-1 >u r> >r-1 >r ; inline
v> >v-1 >v u> >u-1 >u s> >s-1 >s ; inline
: step ( -- )
r-1> r> 2dup /mod drop [ * - ] keep u-1> over u> * - v-1> rot v> * -
s-1> s> 2dup /mod drop [ * - ] keep u-1> over u> * - v-1> rot v> * -
advance ;
PRIVATE>
! Extended Euclidian: http://en.wikipedia.org/wiki/Extended_Euclidean_algorithm
: ext-euclidian ( a b -- gcd u v )
[ init [ r> 0 > ] [ step ] [ ] while r-1> u-1> v-1> ] with-scope ; foldable
[ init [ s> 0 > ] [ step ] [ ] while s-1> u-1> v-1> ] with-scope ; foldable
! Inverse a in ring Z/bZ
: ring-inverse ( a b -- i )