Guardian Native C Library Calls Reference Manual (G06.28+, H06.05+)

atanh(3) Guardian Native C 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 native Guardian processes: $SYSTEM.ZDLLnnn.ZCREDLL
H-series OSS processes: /G/system/zdllnnn/zcredll
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.
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