Open System Services Library Calls Reference Manual (G06.28+, H06.05+)

fabs(3) OSS Library Calls Reference Manual
NAME
fabs - Computes the floating-point absolute value 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 fabs(
double x);
PARAMETERS
x Specifies the double value whose absolute value is to be computed.
DESCRIPTION
The fabs() function returns the absolute value of x,afloating-point number.
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
Upon successful completion, the fabs() function returns the absolute value of x.
For IEEE floating-point values, if the value of x is NaN, NaN is returned. If the value of x is
infinity, positive infinity is returned.
ERRORS
No error values are returned. This function does not set errno.
RELATED INFORMATION
Functions: abs(3), ceil(3), floor(3), fmod(3), fp_class(3), isnan(3).
STANDARDS CONFORMANCE
This function conforms to the XPG4 Version 2 specification with extensions when used for IEEE
floating-point data. This function conforms to the XPG4 Version 2 specification without exten-
sions when used for Tandem floating-point data.
The XPG4 Version 2 specification leaves some features to the implementing vendor to define.
The following features are affected in the HP implementation:
• For IEEE floating-point data, errno is not set to [EDOM] when the value of x is NaN.
• The fabs() function does not cause underflow so errno is not set to [ERANGE].
2−22 Hewlett-Packard Company 527187-007