hv has asked for the wisdom of the Perl Monks concerning the following question:
I can get a modular reciprocal with Pari easily enough, eg:
1 / 3 == Mod(6,17)use Math::Pari qw/ PARI Mod /; my($n, $p) = map PARI($_), (3, 17); my $recip = PARI(1) / Mod($n, $p); print "1 / $n == $recip\n";
The result "Mod(6,17)" is a modular value, representing the equivalence class of integers equivalent to 6 (mod 17), and that's great.
However I now want to get the "6" out of there as an integer for further work, i.e. to get the "common residue" of that modular number. I haven't found anything in the Math::Pari or Pari/GP docs that tells how to do that, and everything I've tried gives an error:
$int = int($recip); PARI: *** incorrect type in comparison. at -e line 1. $int = pari2num($recip); PARI: *** forbidden assignment t_INTMOD --> t_REAL. at -e line 1. $int = pari2iv($recip); PARI: *** incorrect type in gtolong. at -e line 1.
I could pull the value out with a regexp, but that would be silly. Surely there is a simple, efficient way to do this?
Hugo
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Re: Using modular numbers with Math::Pari
by blokhead (Monsignor) on Oct 29, 2009 at 14:24 UTC | |
by hv (Prior) on Oct 29, 2009 at 14:45 UTC |
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