Category: | Miscellaneous |
Author/Contact Info | sthoenna@efn.org ysth |
Description: | A friend was reviewing precalculus (in preparation to return to school after a decade off and place into a real math class), and was working through some maxtrix determinant problems. I wrote this to help her catch arithmetic errors when calculating minors of a larger matrix. I only spent about 15 minutes, so its kind of rough, but I'm pretty satisfied, especially with how the input code handles errors. |
#!/usr/bin/perl use strict; use warnings; sub getmatrix { my $m = []; my $cols; rand()<.85 ? print "Enter matrix:\n" : print "tell me your matrix +and I'll tell you no lies:\n"; while (!$cols || @$m != $cols) { # print "enter row:\n"; my @row = split ' ', <>; if (@row < 2 || $cols && @row != $cols || grep /.\D|^[^\d-]/s, + @row) { print "try that row again:\n"; @row = split ' ', <>; goto &getmatrix if @row < 2 || $cols && @row != $cols || grep /.\D|^[^ +\d-]/s, @row; } $cols ||= @row; push @$m, \@row; } # use Data::Dumper; # print Dumper $m; $m; } sub determine { my $m = shift; my $det = 0; if (@$m == 2) { $det = $m->[0][0] * $m->[1][1] - $m->[0][1] * $m->[1][0]; } else { my @subm = map [@$_[1..$#$_]], @$m; for (0..$#$m) { if ($_ & 1) { $det -= $m->[$_][0] * determine([@subm[0..$_-1,$_+1..$#subm]]) +; } else { $det += $m->[$_][0] * determine([@subm[0..$_-1,$_+1..$ +#subm]]); } } } $det } while (1) { my $m = getmatrix(); my $det = determine($m) || (rand()<.333 ? 0 : rand() < .5 ? 'zippo +' : 'zilch'); print "got: $det\n"; } |
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Replies are listed 'Best First'. | |
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Re: matrix determinants
by Anonymous Monk on Nov 17, 2003 at 05:30 UTC | |
Re: matrix determinants
by etj (Deacon) on Jun 26, 2022 at 00:55 UTC |
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