Guardian Native C Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

atanl(3) Guardian Native C Library Calls Reference Manual
NAME
atanl - Computes the inverse trigonometric tangent function for a long double value
LIBRARY
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>
long double atanl(
long double x);
PARAMETERS
x Is the long double value for which the inverse trigonometric tangent function is
to be computed.
DESCRIPTION
The atanl() function is a long double version of the atan() function; it takes a long double argu-
ment and returns a long double result.
The atanl() function computes the principal value of the arc tangent of x, in the domain
[-π/2, π/2] radians.
NOTES
This function supports both IEEE Std 754-1985 floating-point and Tandem floating-point values
in the native environment. 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 atanl() function returns the principal value of the arc tangent of x.
For IEEE floating-point values, if the value of x is NaN, the atanl() function returns NaN.
If the result would underflow, the atanl() function returns 0.0 (zero).
ERRORS
The atanl() function does not set errno.
RELATED INFORMATION
Functions: acos(3), acosh(3), asin(3), asinh(3), atan(3), atanf(3), atanh(3), atan2(3), catan(3),
catanh(3), cos(3), cosh(3), fp_class(3), isnan(3), sin(3), sinh(3), tan(3), tanh(3).
Files: float(4), math(4).
STANDARDS CONFORMANCE
This function conforms to the ISO/IEC 9899:1999 standard.
This function conforms to the IEEE Std 1003.1, 2004 Edition.
1−46 Hewlett-Packard Company 527192-018