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

atan2l(3) Guardian Native C Library Calls Reference Manual
NAME
atan2l - Computes the inverse trigonometric tangent function of y/x for long double values
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 atan2l(
long double y,
long double x);
PARAMETERS
y Is the long double value denominator for which the inverse trigonometric tangent
function is to be computed.
x Is the long double value numerator for which the inverse trigonometric tangent
function is to be computed.
DESCRIPTION
The atan2l() function is a long double version of the atan2() function; it takes long double argu-
ments and returns a long double result.
The atan2l() function computes the principal value of the arc tangent of y/x, in the domain [-π,
π] radians, using the signs of both parameters to determine the quadrant of the return value.
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 atan2l() function returns the principal value of the arc tangent of y/x.
For IEEE floating-point values, if the value of x or y is NaN, the atan2l() function returns NaN.
If both the value of x and y is positive or negative 0.0 (zero), the atan2l() function returns 0.0
(zero) and sets errno to [EDOM].
For Tandem floating-point values, if both the value of x and y is 0.0 (zero), the atan2l() function
returns HUGE_VALL and sets errno to [EDOM].
ERRORS
If any of the following conditions occurs, the atan2l() function sets errno to the corresponding
value:
[EDOM] Both arguments are 0.0 (zero).
RELATED INFORMATION
Functions: acos(3), acosh(3), asin(3), asinh(3), atan(3), atanh(3), atan2(3), atan2f(3), carg(3),
cos(3), cosh(3), fp_class(3), isnan(3), sin(3), sinh(3), tan(3), tanh(3).
Files: float(4), math(4).
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