Note that it is almost useless to put a integer higher than 6 maybe 7 in the scale parameter.
In some cases this might be needed. But for the simple souls, more than 4 is not required in most of the time.
(PHP 4, PHP 5)
bcsub — Subtract one arbitrary precision number from another
right_operand from the
The left operand, as a string.
The right operand, as a string.
This optional parameter is used to set the number of digits after the decimal place in the result. You can also set the global default scale for all functions by using bcscale().
The result of the subtraction, as a string.
Example #1 bcsub() example
$a = '1.234';
$b = '5';
echo bcsub($a, $b); // -3
echo bcsub($a, $b, 4); // -3.7660