This one has no tolerance - it should always be exact (except in the case of overflowing the bounds of integer arithmetic for your architecture).

use 5.010;

say fraction_for_decimal($_)
    for qw( 0.3456 1.251 -0.1 -0.25 );

sub fraction_for_decimal
{
    my $decimal = shift;
    my $mult    = 10 ** length [ split m{[.]}, $decimal ]->[1];
    my ($num, $den) = (int($decimal * $mult), $mult);
    my $hcf = _hcf($num, $den);
    $_ /= $hcf for ($num, $den);
    return "$num/$den";
}

# Stolen from Number::Fraction.
sub _hcf {
    my ($x, $y) = @_;
    ($x, $y) = ($y, $x) if $y > $x;
    return $x if $x == $y;
    while ($y) {
        ($x, $y) = ($y, $x % $y);
    }
    return abs($x);  # changed this
}

__END__
216/625
1251/1000
-1/10
-1/4

[download]
perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re: Decimals to fractions by tobyink
in thread Decimals to fractions by oko1

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