HP-UX Reference (11i v2 07/12) - 3 Library Functions A-M (vol 6)

e
exp(3M) exp(3M)
NAME
exp( ), expf(), expl( ), expw( ), expq() - exponential functions
SYNOPSIS
#include <math.h>
double exp(double x);
float expf(float x);
Itanium(R)-based System Only
long double expl(long double x);
extended expw(extended x);
quad expq(quad x);
DESCRIPTION
exp() returns e
x
.
expf() is a float version of exp(); it takes a float argument and returns a float
result.
Itanium-based System Only
expl() is a long double version of exp(); it takes a long double argument and returns a
long double result.
expw() is an extended version of exp(); it takes an extended argument and returns an
extended result.
expq() is equivalent to expl() on HP-UX systems.
USAGE
To use these functions compile either with the default -Ae option or with the -Aa
and the
-D_HPUX_SOURCE options.
To use (for Itanium-based systems)
expw() or expq(), compile also with the -fpwidetypes option.
To use any of these functions, make sure your program includes
<math.h>, and link in the math library
by specifying -lm on the compiler or linker command line.
For more information, see the HP-UX Floating-Point Guide.
PA-RISC Only
Millicode versions of the
exp() functions are available. Millicode versions of math library functions are
usually faster than their counterparts in the standard library. To use these versions, compile your program
with the +Olibcalls or the +Oaggressive optimization option.
For special cases, the millicode versions return the same values as their standard library counterparts (see
the RETURN VALUE section), but do not set errno.
RETURN VALUE
exp(±0) returns 1.
If x is +INFINITY, exp() returns +INFINITY.
If x is −INFINITY, exp() returns +0.
If x is NaN, exp() returns NaN.
exp() returns infinity (equal to HUGE_VAL) in lieu of a value whose magnitude is too large, and raises
the overflow and inexact exceptions.
exp() raises the underflow and inexact exceptions whenever a result is tiny (essentially denormal or zero)
and thereby suffers loss of accuracy, and may raise those exceptions if the result is merely tiny.
When it raises no other exception, whether exp() raises the inexact exception is unspecified.
ERRORS
If the correct value would overflow, exp() sets errno to [ERANGE].
HP-UX 11i Version 2: December 2007 Update − 1 − Hewlett-Packard Company 381