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Perl: the Markov chain saw

renz's scratchpad

by renz (Scribe)
on Jan 14, 2005 at 21:55 UTC ( #422406=scratchpad: print w/replies, xml ) Need Help??

#!/usr/bin/perl -w #, v2.0 - test for primality # thanks to: mr_mischief for help and efficient isPrime() rewrite. # also: i prefer the code TedPride uses in node 430254 to find the # highest divisor, so i have modified my own here.. use strict; use warnings; @ARGV or die &usage; print "\n[RESULTS]\n\n"; foreach my $num (@ARGV) { isPrime($num); } sub isPrime { my $num = $_[0]; my $val = 'prime'; if ($num =~ /^\d+$/ && $num >= 2) { my $mod = 2; my $div = int sqrt $num; while ($mod <= $div) { ($num % $mod) == 0 ? ($val = 'composite', last) : $mod++; } } else { $val = 'neither'; } print ' ' . $num . ":\t\t$val\n"; } sub usage { print "\nUsage: " . $0 . " <number(s)>\n"; print "\n\tOnly real, whole numbers greater than one can be prime. +\n"; exit 1; } # rz/021005

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[shmem]: holli: all of our machinery is more perfect in its realm than any human being in theirs (Günther Anders), which doesn't mean not having fun, albeit dangerous sometimes.
[ww]: That's a big "if", holli.
[holli]: well the google car drove 5 times as far as the average human without an accident didnt it?
[ww]: Less than confident that ai+hardware is up (yet) to randomness and counterintuitive behavior on streets of NY
[ww]: (and having lived both, Boston traffic challenges are even >.

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