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

OSS Library Calls (e - f) expm1f(3)
NAME
expm1f - Computes the exponential function minus 1.0 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 expm1f(
float x);
PARAMETERS
x Is the power to which the base of the natural logarithms (e)istoberaised.
DESCRIPTION
The expm1f( ) function is a float version of the expm1( ) function; it takes a float argument and
returns a float result.
The expm1f( ) function computes the value of e raised to the power x and subtracts 1.0 to get the
final result.
NOTES
The expm1f( ) 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 (zero) can be either positive or nega-
tive. 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
For IEEE floating-point values, when the value of x is NaN, the expm1f( ) function returns NaN.
When x is positive infinity, the expm1f( ) function returns positive infinity. When x is negative
infinity, the expm1f( ) function returns -1.0.
When the calculated value would cause overflow, the expm1f( ) function returns HUGE_VALF
and sets errno to [ERANGE].
ERRORS
If any of the following conditions occurs, the expm1f( ) function sets errno to the corresponding
value:
[ERANGE] The calculated result would cause overflow.
RELATED INFORMATION
Functions: expm1(3), expm1l(3), fp_class(3), isnan(3).
STANDARDS CONFORMANCE
This function conforms to the ISO/IEC 9899:1999 standard.
This function conforms to the IEEE Std 1003.1, 2004 Edition.
527187-017 Hewlett-Packard Company 2−33