/C

# exp2, exp2f, exp2l

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

```#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)

 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`