# libm.info: Math

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# Mathematical Functions (`math.h')

This chapter groups a wide variety of mathematical functions. The
corresponding definitions and declarations are in `math.h'. Two
definitions from `math.h' are of particular interest.

1. The representation of infinity as a `double' is defined as
`HUGE_VAL'; this number is returned on overflow by many functions.

2. The structure `exception' is used when you write customized error
handlers for the mathematical functions. You can customize error
handling for most of these functions by defining your own version
of `matherr'; see the section on `matherr' for details.

Since the error handling code calls `fputs', the mathematical
subroutines require stubs or minimal implementations for the same list
of OS subroutines as `fputs': `close', `fstat', `isatty', `lseek',
`read', `sbrk', `write'. *Note System Calls: (libc.info)syscalls, for
a discussion and for sample minimal implementations of these support
subroutines.

Alternative declarations of the mathematical functions, which exploit
specific machine capabilities to operate faster--but generally have
less error checking and may reflect additional limitations on some
machines--are available when you include `fastmath.h' instead of
`math.h'.

Created Mon Nov 8 17:42:56 2004 on tillpc with info_to_html version 0.9.6.