Guardian Native C Library Calls Reference Manual (G06.28+, H06.04+)

Guardian Native C Library Calls (a - e) asin(3)
NAME
asin - Computes the inverse trigonometric sine 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 asin(
double x);
PARAMETERS
x Is the value for which the inverse trigonometric sine function is to be computed.
DESCRIPTION
The asin() function computes the principal value of the arc sine of x, in the domain [-π/2, π/2]
radians. The value of x must be in the domain [-1,+1].
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 asin() function returns the principal value of the arc sine of x.
For IEEE floating-point values, if the value of x is NaN, the asin() function returns NaN. If the
value of x is positive or negative infinity, the asin() function returns NaN and sets errno to
[EDOM]. If the value of x is not in the domain [-1, 1], the asin() function returns NaN and sets
errno to [EDOM].
For Tandem floating-point values, if the value of x is not in the domain [-1, 1], the asin() function
returns 0.0 (zero) and sets errno to [EDOM].
If the result would cause underflow, the asin() function returns 0.0 (zero).
ERRORS
If any of the following conditions occurs, the asin() function sets errno to the corresponding
value:
[EDOM] The the value of the x parameter is infinite or not in the domain [-1,+1].
RELATED INFORMATION
Functions: acos(3), acosh(3), asin(3), asinh(3), atan(3), atan2(3), atanh(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 XPG4 Version 2 specification with extensions when used for IEEE
floating-point format data. This function conforms to the XPG4 Version 2 specification without
extensions when used for Tandem floating-point data.
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