Perlで任意精度計算

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YAPC::Asia Tokyo 2010 presentation

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  • Perlで任意精度計算

    1. 1. 3.14159 26535 89793 23846 26433 83279 50288.....
    2. 2. use Math::BigFloat; my $x = Math::BigFloat->new(‘3.1415...’); my $y = Math::BigFloat->new(‘2.718281...’); my $z = $x * $y;
    3. 3. # my $pi = Math::BigFloat->new(3.141592...); # my $pi = Math::BigFloat->new(‘3.141592...’);
    4. 4. use strict; use Math::BigFloat; use Benchmark qw(cmpthese); cmpthese -1, {     plain => sub {         my $x = rand(10);         my $y = rand(10);         my $z = rand(10);         ($x + $y ) * $z;     },     bigfloat => sub {         my $x = rand(10);         my $y = rand(10);         my $z = rand(10);         (Math::BigFloat->new($x) + Math::BigFloat->new($y)) * Math::BigFloat->new($z);     }, };
    5. 5. daisuke@beefcake ~$ perl foo.pl               Rate bigfloat plain bigfloat 3380/s -- -100% plain 2383127/s 70403% -- daisuke@beefcake ~$ perl foo.pl               Rate bigfloat plain bigfloat 3380/s -- -100% plain 2360644/s 69738% -- daisuke@beefcake ~$ perl foo.pl               Rate bigfloat plain bigfloat 3380/s -- -100% plain 2406041/s 71081% --
    6. 6. > perl benchmark.pl Rate bigfloat plain bigfloat 3901/s -- -100% plain 2338582/s 59849% --
    7. 7. •DateTime::Util::Calc •DateTime::Util::Astro •DateTime::Event::Lunar
    8. 8. my $v = ( $x + $y ) * $z; #include <mpfr.h> mpfr_t x, y, z, w; mpfr_add( w, x, y, MPFR_RNDN ); mpfr_mul( w, w, z, MPFR_RNDN );
    9. 9. mpfr_add( w, x, y, MPFR_RNDN );
    10. 10. s/iter bigint xs bigint 2.58 -- -98% mpfr 4.70e-02 5394% --

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