exp2

, exp2f

, exp2l

- exponential base 2 functions

Synopsis

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

double exp2(double x);

float exp2f(float x);

long double exp2l(long double x);

Description

These functions compute the base-2 exponential of x.

Return Values

Upon successful completion, these functions return 2^x.

If the correct value would cause overflow, a range error occurs and exp2(), exp2f(), and exp2l() return the value of the macro 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, +0 is returned.

If x is +Inf, x is returned.

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 will be raised.

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.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

exp(3M), feclearexcept(3M), fetestexcept(3M), isnan(3M), log(3M), math.h(3HEAD), attributes(5), standards(5)