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

acosf(3) OSS Library Calls Reference Manual
NAME
acosf - Computes the inverse trigonometric cosine function for a float 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>
float acosf(
float x);
PARAMETERS
x Is the float value for which the inverse trigonometric cosine function is to be
computed.
DESCRIPTION
The acosf( ) function is a float version of the acos( ) function; it takes a float argument and returns
a float result.
The acosf( ) function computes the principal value of the arc cosine of x, in the range [0, π] radi-
ans. 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 acosf( ) function returns the principal value of the arc cosine of x.
For IEEE floating-point values, if the value of x is NaN, the acosf( ) function returns NaN. If the
value of x is positive or negative infinity, the acosf( ) function returns NaN and sets errno to
[EDOM]. If the value of x is not in the domain [-1, +1], the acosf( ) 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 acosf( ) func-
tion returns 0.0 (zero) and sets errno to [EDOM].
ERRORS
If the following condition occurs, the acosf( ) function sets errno to the corresponding value:
[EDOM] The value of the x parameter is infinite or not in the domain [-1,+1].
RELATED INFORMATION
Functions: acos(3), acosl(3), acosh(3), asin(3), asinh(3), atan(3), atan2(3), atanh(3), cacos(3),
cacosh(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.
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