Experiments with dividing really big integers into Num

smartdiv.pl

sub guess_size(Int $a is copy) {
    $a = abs $a;
    my $ref = 2**16;
    my $c = 0;
    while $a > $ref {
        $a div= $ref;
        $c += 16
    }
    $c;
}

sub DIVIDE(Int $a, Int $b) {
    my Int $sa = guess_size $a;
    my Int $sb = guess_size $b;
    my Int $max_size = $sa max $sb;
    # the exponent of a 64bit integer goes up to 1023
    # and guess_size underestimates by at most 15 bit
    if $max_size > 1008 {
        my Int $div = 2**($max_size - 1008);
        return ($a div $div).Num / ($b div $div).Num;
    }
    $a.Num / $b.Num;
}

say DIVIDE(203**200, 200**200) - (203e0 / 200e0)**200;
# output: 3.76587649952853e-13