exp2, exp2f, exp2l - cppreference.com (original) (raw)

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.

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.

[edit] Parameters

[edit] 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.

[edit] 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

[edit] Example

#include <errno.h> #include <fenv.h> #include <float.h> #include <math.h> #include <stdio.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(-0.9) = %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(-0.9) = 0.535887 exp2(-Inf) = 0.000000 exp2(1024) = Inf errno == ERANGE: Result too large FE_OVERFLOW raised

[edit] References