exp2, exp2f, exp2l

 

C

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

 

Numerics

Common mathematical functions

Floating-point environment

Complex number arithmetics

Random number generation

Type-generic math

 

Common mathematical functions

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 (2n
) 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)

See also

expexpfexpl (C99)(C99)	computes e raised to the given power (ex) (function)
expm1expm1fexpm1l (C99)(C99)(C99)	computes e raised to the given power, minus one (ex-1) (function)
log2log2flog2l (C99)(C99)(C99)	computes base-2 logarithm (log2(x)) (function)
C++ documentation for exp2