Open System Services Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

atanh(3) OSS Library Calls Reference Manual
NAME
atanh - Computes the inverse hyperbolic tangent function
LIBRARY
G-series native Guardian processes: $SYSTEM.SYSnn.ZCRESRL
G-series native OSS processes: /G/system/sysnn/zcresrl
H-series and J-series native Guardian processes: $SYSTEM.ZDLLnnn.ZCREDLL
32-bit H-series and J-series OSS processes: /G/system/zdllnnn/zcredll
64-bit H-series and J-series OSS processes: /G/system/zdllnnn/ycredll
SYNOPSIS
#include <math.h>
double atanh(
double x);
PARAMETERS
x Is the value for which the inverse hyperbolic tangent function is to be computed.
DESCRIPTION
The atanh( ) function computes the inverse hyperbolic tangent of x.
The atanh( ) function can be called only by native processes.
NOTES
This function supports both IEEE Std 754-1985 floating-point and Tandem floating-point values.
IEEE values can include NaN and infinity, and the sign of 0.0 (zero) can be either positive or
negative. Refer to the fp_class(3) reference page for a description of IEEE value classes.
Guardian functions are available to convert between floating-point formats. Refer to the Guar-
dian Programmer’s Guide for a discussion of floating-point conversions.
RETURN VALUES
The atanh( ) function returns the inverse hyperbolic tangent of the x parameter.
For IEEE floating-point values, when the value of x is NaN, the atanh( ) function returns NaN.
When the absolute value of x is 1.0, the atanh( ) function returns +HUGE_VAL or
-HUGE_VAL as appropriate and sets errno to [ERANGE]. When the absolute value of x is
greater than 1.0, the atanh( ) function returns NaN and sets errno to [EDOM].
For Tandem floating-point values, when the absolute value of x is 1.0, the atanh( ) function
returns +HUGE_VAL or -HUGE_VAL as appropriate and sets errno to [ERANGE]. When the
absolute value of x is greater than 1.0, the atanh( ) function returns HUGE_VAL and sets errno
to [EDOM].
ERRORS
If any of the following conditions occur, the atanh( ) function sets errno to the corresponding
value:
[EDOM] The absolute value of the x parameter is greater than 1.0.
[ERANGE] The absolute value of the x parameter is equal to 1.0.
RELATED INFORMATION
Functions: asin(3), asinh(3), acos(3), acosh(3), atan(3), atan2(3), fp_class(3), isnan(3).
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