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More efficient polyval algorithm in math.polynomials

db4
Doug Coleman 2011-02-12 22:41:13 -06:00
parent 02ecc45165
commit fd7e5ffee8
2 changed files with 10 additions and 1 deletions
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6
basis/math/polynomials/polynomials-tests.factor
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@ -33,3 +33,9 @@ IN: math.polynomials.tests
[ { 10 200 3000 } ] [ { 1 10 100 1000 } pdiff ] unit-test [ { 10 200 3000 } ] [ { 1 10 100 1000 } pdiff ] unit-test
[ { -512 2304 -4608 5376 -4032 2016 -672 144 -18 1 } ]
[ { -2 1 } 9 p^ ] unit-test
[ 0 ]
[ 2 { -2 1 } 9 p^ polyval ] unit-test

5
basis/math/polynomials/polynomials.factor
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@ -91,7 +91,10 @@ PRIVATE>
dup length iota v* rest ; dup length iota v* rest ;
: polyval ( x p -- p[x] ) : polyval ( x p -- p[x] )
[ length swap powers ] [ nip ] 2bi v. ; ! Horner scheme
[ nip <reversed> unclip-slice swap ]
[ drop ] 2bi
'[ [ _ * ] dip + ] each ;
MACRO: polyval* ( p -- ) MACRO: polyval* ( p -- )
reverse reverse