I'm trying to find a better way to round the last digit of some fractional numbers.

All my numbers match this:        /^0\.\d{5,}9{3}\d$/

The numbers will always be rounded "up" (like in POSIX::ceil, but in a fractional context).

    0.123499999996   rounds to 0.1235
    0.12345678999994 rounds to 0.12345679

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This is what I have so far: (adds 0.00000000000006 to 0.12345678999994 giving 0.12345679)

if ($frac =~ /999.$/) {
    my ($zeroes, $digit) = $frac =~ /\.(.*)(.)$/;
    $digit = '0.' . 
        '0' x (length($zeroes)-1) .
        sprintf("%02d", 10 - $digit);
    $frac += $digit;
}

[download]

In reply to Round a fraction by fglock

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