Qed (pronounced "ked") provides method chaining on BCMath operations, allowing you to write smoother and more readable calculation code.

Qed also includes polyfill functions for bcround, bcceil, and bcfloor, which have official implementations coming in a future PHP release.

(Note that Qed's polyfills are not guaranteed to be mathematically sound. Please don't use them for anything even the slightest bit important.)

A set of basic operations:

$num = new Qed('123');
$num = $num->add('27')->mul('4');

echo $num->value; // 600

Setting the scale:

BCMath operations have a concept of a "scale factor". This can become quite important - certain numbers may end up being unintentionally truncated if the scale is not set to a suitable value.

Scale may be a bit different than precision. For more information, see the bcscale() documentation on the PHP website.

$num = new Qed('123', 5);
$divisor = new Qed('456');
$num = $num->div($divisor)->mul('10');

echo $num->value; // 2.69730

Note that the scale follows the left-side of the flow. If a Qed object is passed as the divisor (or any other operand), that object's scale will be ignored.

Rounding:

While bcround() isn't yet available in PHP, Qed provides a polyfill function and a helper method. This polyfill function is primitive and deeply unreliable.

But, if you want to risk it, here's how to use it:

$num = new Qed('123', 10);
$divisor = new Qed('456');
$num = $num->div($divisor)->mul('10')->round(2);

echo $num->value; // 2.70

Note that the precision value is NOT the same as a normal "scale" value, because scale factor cannot be a negative value (but precision can). The returned Qed object will have the same scale value as the originating instance, the precision value is only applied to the internals of bcround.

There is a second parameter, $roundHalf, which can be one of the PHP_ROUND_HALF_* constants. See php.net/round for more information about how they are expected to work.