Guardian Native C Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

expf(3) Guardian Native C Library Calls Reference Manual
NAME
expf - Computes the exponential 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 expf(
float x);
PARAMETERS
x Specifies the power to which the base of the natural logarithms (e)istoberaised.
DESCRIPTION
The expf() function is a float version of the exp() function; it takes a float argument and returns a
float result.
The expf() function computes the exponential function of x, defined as e
x
, where e is the constant
used as a base for natural logarithms.
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, expf() returns the value of the exponential function of x. If the
correct value would cause overflow, the expf() function returns HUGE_VALF and sets errno to
[ERANGE]. If the correct value would cause underflow, the expf() function returns a value of
0.0 (zero) and sets errno to [ERANGE].
For IEEE floating-point data, if the value of x is NaN, NaN is returned. If the value of x is posi-
tive infinity, positive infinity is returned.
ERRORS
If any of the following conditions occurs, the expf() function sets errno to the corresponding
value:
[ERANGE] The result would cause underflow or overflow.
RELATED INFORMATION
Functions: exp(3), expl(3), expm1(3), fp_class(3), isnan(3), log(3), log10(3), pow(3), sinh(3).
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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