IV. BCMath Arbitrary Precision Mathematics Functions


For arbitrary precision mathematics PHP offers the Binary Calculator which supports numbers of any size and precision, represented as strings.


Since PHP 4.0.4, libbcmath is bundled with PHP. You don't need any external libraries for this extension.


In PHP 4, these functions are only available if PHP was configured with --enable-bcmath. In PHP 3, these functions are only available if PHP was NOT configured with --disable-bcmath.

The windows version of PHP has built in support for this extension. You do not need to load any additional extension in order to use these functions.

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Table 1. BC math configuration options

For further details and definition of the PHP_INI_* constants see ini_set().

Here is a short explanation of the configuration directives.

bcmath.scale integer

Number of decimal digits for all bcmath functions.

Resource Types

This extension has no resource types defined.

Predefined Constants

This extension has no constants defined.

Table of Contents
bcadd -- Add two arbitrary precision numbers
bccomp -- Compare two arbitrary precision numbers
bcdiv -- Divide two arbitrary precision numbers
bcmod --  Get modulus of an arbitrary precision number
bcmul -- Multiply two arbitrary precision number
bcpow --  Raise an arbitrary precision number to another
bcpowmod --  Raise an arbitrary precision number to another, reduced by a specified modulus.
bcscale --  Set default scale parameter for all bc math functions
bcsqrt --  Get the square root of an arbitrary precision number
bcsub --  Subtract one arbitrary precision number from another