exp2, exp2f, exp2l
Defined in header <math.h>
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(1) | (since C99) |
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(2) | (since C99) |
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(3) | (since C99) |
Defined in header <tgmath.h>
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(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 (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 (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) |
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