log

log EXPR

log

Returns the natural logarithm (base e) of EXPR. If EXPR is omitted, returns the log of $_ . To get the log of another base, use basic algebra: The base-N log of a number is equal to the natural log of that number divided by the natural log of N. For example:

sub log10 {
    my $n = shift;
    return log($n)/log(10);
}

See also exp for the inverse operation.