exp2, exp2f, exp2l
From cppreference.com
| 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(-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 raisedReferences
- 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
| (C99)(C99) |
computes e raised to the given power (ex) (function) |
| (C99)(C99)(C99) |
computes e raised to the given power, minus one (ex-1) (function) |
| (C99)(C99)(C99) |
computes base-2 logarithm (log2(x)) (function) |