illumos: manual page: exp.3m

EXP(3M) Mathematical Library Functions EXP(3M)

NAME

exp, expf, expl - exponential function

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double exp(double x);

float expf(float x);

long double expl(long double x);

DESCRIPTION

These functions compute the base-e exponential of x.

RETURN VALUES

Upon successful completion, these functions return the exponential value
of x.

If the correct value would cause overflow, a range error occurs and
exp(), expf(), and expl() return HUGE_VAL, HUGE_VALF, and HUGE_VALL,
respectively.

If x is NaN, a NaN is returned.

If x is +-0, 1 is returned.

If x is +Inf, x is returned.

For exceptional cases, matherr(3M) tabulates the values to be returned by
exp() as specified by SVID3 and XPG3. See standards(7).

ERRORS

These functions will fail if:

Range Error
The result overflows.

If the integer expression (math_errhandling &
MATH_ERREXCEPT) is non-zero, the overflow floating-point
exception is raised.

The exp() function sets errno to ERANGE if the result
overflows.

USAGE

An application wanting to check for exceptions should call
feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return,
if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW)
is non-zero, an exception has been raised. An application should either
examine the return value or check the floating point exception flags to
detect exceptions.

An application can also set errno to 0 before calling exp(). On return,
if errno is non-zero, an error has occurred. The expf() and expl()
functions do not set errno.

ATTRIBUTES