Computers generally don't handle floating point numbers the way we expect them to. For instance, while you might think a number is 4.3, the computer might store it as 4.2999999999999. For most applications, this is probably fine, but you have to round the results when you display them. To compare two floating point numbers, use the sprintf function, figure out how many significant digits you need and compare with a string equal comparison operator (eq).

sub floats_eq {
    my ($num1, $num2, $sig) = @_;
    $_ = sprintf "%.${sig}g" foreach $num1, $num2;
    return $num1 eq $num2;
}
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