Copyright (C) 1992, 1993 Cygnus Support

`libm' includes software developed by the University of California, Berkeley and its contributors.

`libm' includes software developed by Martin Jackson, Graham Haley and Steve Chamberlain of Tadpole Technology and released to Cygnus.

`libm' includes software developed at SunPro, a Sun Microsystems, Inc. business. Permission to use, copy, modify, and distribute this software is freely granted, provided that this notice is preserved.

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Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, subject to the terms of the GNU General Public License, which includes the provision that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

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• Math: The mathematical functions (`math.h').
• Reentrancy: The functions in libm are not reentrant by default.
• Index

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. See section `System Calls' in The Cygnus C Support Library, 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'.

• version: Version of library
• acos: Arccosine
• acosh: Inverse hyperbolic cosine
• asin: Arcsine
• asinh: Inverse hyperbolic sine
• atan: Arctangent
• atan2: Arctangent of y/x
• atanh: Inverse hyperbolic tangent
• jN: Bessel functions (jN, yN)
• cbrt: Cube root
• copysign: Sign of Y, magnitude of X
• cosh: Hyperbolic cosine
• erf: Error function (erf, erfc)
• exp: Exponential
• expm1: Exponential of x, - 1
• fabs: Absolute value (magnitude)
• floor: Floor and ceiling (floor, ceil)
• fmod: Floating-point remainder (modulo)
• frexp: Split floating-point number
• gamma: Logarithmic gamma function
• hypot: Distance from origin
• ilogb: Get exponent
• infinity: Floating infinity
• isnan: Check type of number
• ldexp: Load exponent
• log: Natural logarithms
• log10: Base 10 logarithms
• log1p: Log of 1 + X
• matherr: Modifiable math error handler
• modf: Split fractional and integer parts
• nan: Floating Not a Number
• nextafter: Get next representable number
• pow: X to the power Y
• rint: Round and remainder (rint, remainder)
• scalbn: Scale number
• sin: Sine or cosine (sin, cos)
• sinh: Hyperbolic sine
• sqrt: Positive square root
• tan: Tangent
• tanh: Hyperbolic tangent