LOG(): The logarithm of a number to base

<?Php
echo LOG(2);// Output is 0.69314718055995
echo "<br>";
echo LOG(-1);// Output is NAN
echo "<br>";
echo LOG(0);// Output is -INF
echo "<br>";
echo LOG(5.7);// Output is 1.7404661748405
?>

LOG(X,Y);

LOG() with Base

<?Php
echo LOG(5,2);// Output is 2.3219280948874
echo "<br>";
echo LOG(5,10);// Output is 0.69897000433602 
echo "<br>";
echo LOG(5,2.7183);// Output is 1.609427153552
?>

Questions