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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.


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.

BC math configuration options
Name Default Changeable Changelog
bcmath.scale "0" PHP_INI_ALL  
For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

bcmath.scale integer

Number of decimal digits for all bcmath functions. See also bcscale().

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