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# IV. BCMath Arbitrary Precision Mathematics Functions

# Introduction

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

# Requirements

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

# Installation

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`.

# Runtime Configuration

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

Table 1. BC math configuration options

Name | Default | Changeable
--- | --- | ---
bcmath.scale | 0 | PHP_INI_ALL

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.

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