Re: log() and int() problem

log returns a floating-point number, so the results are prone to floating-point inaccuracies:

$ perl -wE 'printf "%.20f\n", log(125)/log(5)'
3.00000000000000044409
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A safer test is something like this here, which only uses integers:

use strict;
use warnings;
use 5.010;

sub is_power_of {
    my ($num, $base) = @_;

    while ($num > 1) {
        return 0 if $num % $base != 0;
        $num /= $base;
    }
    return 1;
}

say is_power_of(125, 5);
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Perl 6 - the future is here, just unevenly distributed

Comment on Re: log() and int() problem Select or Download Code

Replies are listed 'Best First'.
Re^2: log() and int() problem by Anonymous Monk on Dec 25, 2012 at 21:35 UTC
Idly curious why a loop and "/=" are needed. Not questioning but curious. Example?	[reply]
Re^3: log() and int() problem by Anonymous Monk on Dec 25, 2012 at 23:17 UTC
Add `print "$num\n";` and you can see how the loop works	[reply] [d/l]

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