# log - perldoc - [phpMan]

    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)](https://www.chedong.com/phpMan.php/man/log/10/markdown);
                }

            See also "exp" for the inverse operation.