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Base Operating System and Extensions Technical Reference, Volume 1

asinh, acosh, or atanh Subroutine

Purpose

Computes inverse hyperbolic functions.

Libraries

IEEE Math Library (libm.a) or System V Math Library (libmsaa.a)

Syntax

#include <math.h>
double asinh (x)
double x;
double acosh (x)
double x;
double atanh (x)
double x;

Description

The asinh, acosh, and atanh subroutines compute the inverse hyperbolic functions.

The asinh subroutine returns the hyperbolic arc sine specified by the x parameter, in the range of the -HUGE_VAL value to the +HUGE_VAL value. The acosh subroutine returns the hyperbolic arc cosine specified by the x parameter, in the range 1 to the +HUGE_VAL value. The atanh subroutine returns the hyperbolic arc tangent specified by the x parameter, in the range of the -HUGE_VAL value to the +HUGE_VAL value.

Note: Compile any routine that uses subroutines from the libm.a library with the -lm flag. For example: to compile the asinh.c file, enter:
cc asinh.c -lm

Parameters

x Specifies a double-precision floating-point value.

Error Codes

The acosh subroutine returns NaNQ (not-a-number) and sets errno to EDOM if the x parameter is less than the value of 1.

The atanh subroutine returns NaNQ and sets errno to EDOM if the absolute value of x is greater than 1.

Implementation Specifics

These subroutines are part of Base Operating System (BOS) Runtime.

Related Information

The copysign, nextafter, scalb, logb, or ilogb subroutine, exp, expm1, log, log10, or pow subroutine, sinh, cosh, or tanh subroutine.

Subroutines Overview in AIX General Programming Concepts: Writing and Debugging Programs.


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