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

erf(3) OSS Library Calls Reference Manual
NAME
erf - Computes the error function
LIBRARY
G-series native Guardian processes: $SYSTEM.SYSnn.ZCRESRL
G-series native OSS processes: /G/system/sysnn/zcresrl
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>
double erf(
double x);
PARAMETERS
x Specifies the double value for which the error function is to be computed.
DESCRIPTION
The erf() function computes the error function of x, defined as:
√
π
2
___
0
∫
x
e
−t
2
dt
NOTES
The erf() function can be called only by native processes.
This function supports both IEEE Std 754-1985 floating-point and Tandem floating-point values.
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 erf( ) function returns the value of the error function.
For IEEE floating-point values, if the value of x is NaN, NaN is returned.
If the correct value would cause underflow, 0.0 (zero) is returned.
ERRORS
No errors are returned. This function does not set errno.
RELATED INFORMATION
Functions: erfc(3), exp(3), fp_class(3), isnan(3).
STANDARDS CONFORMANCE
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.
• errno is not set to [ERANGE] when the result would cause underflow.
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