exp2, exp2f, exp2l

Functions

Basic operations

abslabsllabsimaxabs (C99)
fabs
divldivlldivimaxdiv (C99)
fmod

remainder (C99)
remquo (C99)
fma (C99)
fmax (C99)
fmin (C99)
fdim (C99)
nannanfnanl (C99)(C99)(C99)

Exponential functions

exp
exp2 (C99)
expm1 (C99)

log
log10
log1p (C99)
log2 (C99)

Power functions

sqrt
cbrt (C99)

hypot (C99)
pow

Trigonometric and hyperbolic functions

sin
cos
tan
asin
acos
atan
atan2

sinh
cosh
tanh
asinh (C99)
acosh (C99)
atanh (C99)

Error and gamma functions

erf (C99)
erfc (C99)

lgamma (C99)
tgamma (C99)

Nearest integer floating point operations

ceil
floor
roundlroundllround (C99)(C99)(C99)

trunc (C99)
nearbyint (C99)
rintlrintllrint (C99)(C99)(C99)

Floating point manipulation functions

ldexp
scalbnscalbln (C99)(C99)
ilogb (C99)
logb (C99)

frexp
modf
nextafternexttoward (C99)(C99)
copysign (C99)

Classification

fpclassify (C99)
isfinite (C99)
isinf (C99)
isnan (C99)
isnormal (C99)
signbit (C99)

isgreater (C99)
isgreaterequal (C99)
isless (C99)
islessequal (C99)
islessgreater (C99)
isunordered (C99)

Types

div_tldiv_tlldiv_timaxdiv_t

(C99)(C99)

float_tdouble_t

(C99)(C99)

Macro constants

HUGE_VALFHUGE_VALHUGE_VALL (C99)(C99)
FP_FAST_FMAFFP_FAST_FMAFP_FAST_FMAL (C99)(C99)(C99)
math_errhandlingMATH_ERRNOMATH_ERRNOEXCEPT (C99)(C99)(C99)

INFINITY (C99)
NAN (C99)
FP_ILOGB0FP_ILOGBNAN (C99)(C99)
FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99)

Defined in header `<math.h>`
float exp2f( float n );	(1)	(since C99)
double exp2( double n );	(2)	(since C99)
long double exp2l( long double n );	(3)	(since C99)
Defined in header `<tgmath.h>`
#define exp2( n )	(4)	(since C99)

1-3) Computes 2 raised to the given power n.

4) Type-generic macro: If n has type long double, exp2l is called. Otherwise, if n has integer type or the type double, exp2 is called. Otherwise, exp2f is called.

Parameters

n

-

floating point value

Return value

If no errors occur, the base-2 exponential of n ( $2 n$ ) is returned.

If a range error due to overflow occurs, +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL is returned.

If a range error occurs due to underflow, the correct result (after rounding) is returned.

Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

If the argument is ±0, 1 is returned
If the argument is -∞, +0 is returned
If the argument is +∞, +∞ is returned
If the argument is NaN, NaN is returned

Example

Run this code

#include <stdio.h>
#include <math.h>
#include <float.h>
#include <errno.h>
#include <fenv.h>
#pragma STDC FENV_ACCESS ON
int main(void)
{
    printf("exp2(5) = %f\n", exp2(5));
    printf("exp2(0.5) = %f\n", exp2(0.5));
    printf("exp2(-4) = %f\n", exp2(-4));
    // special values
    printf("exp2(-9) = %f\n", exp2(-0.9));
    printf("exp2(-Inf) = %f\n", exp2(-INFINITY));
    //error handling
    errno = 0; feclearexcept(FE_ALL_EXCEPT);
    printf("exp2(1024) = %f\n", exp2(1024));
    if(errno == ERANGE) perror("    errno == ERANGE");
    if(fetestexcept(FE_OVERFLOW)) puts("    FE_OVERFLOW raised");
}

Possible output:

exp2(5) = 32.000000
exp2(0.5) = 1.414214
exp2(-4) = 0.062500
exp2(-9) = 0.535887
exp2(-Inf) = 0.000000
exp2(1024) = Inf
    errno == ERANGE: Result too large
    FE_OVERFLOW raised

References

C11 standard (ISO/IEC 9899:2011):

7.12.6.2 The exp2 functions (p: 242-243)

7.25 Type-generic math <tgmath.h> (p: 373-375)

F.10.3.2 The exp2 functions (p: 521)

C99 standard (ISO/IEC 9899:1999):

7.12.6.2 The exp2 functions (p: 223)

7.22 Type-generic math <tgmath.h> (p: 335-337)

F.9.3.2 The exp2 functions (p: 458)

Language
Headers
Type support
Program utilities
Variadic function support
Error handling
Dynamic memory management
Date and time utilities
Strings library
Algorithms
Numerics
Input/output support
Localization support
Atomic operations (C11)
Thread support (C11)
Technical Specifications

Common mathematical functions
Floating-point environment
Complex number arithmetics
Random number generation
Type-generic math