exp2, exp2f, exp2l
From cppreference.com
| Defined in header <math.h>
|
||
float exp2f( float n );
|
(1) | (since C99) |
double exp2( double n );
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(2) | (since C99) |
long double exp2l( long double n );
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(3) | (since C99) |
| Defined in header <tgmath.h>
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#define exp2( n )
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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
Run this code
#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
References
- C23 standard (ISO/IEC 9899:2024):
- 7.12.6.2 The exp2 functions (p: TBD)
- 7.25 Type-generic math <tgmath.h> (p: TBD)
- F.10.3.2 The exp2 functions (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.12.6.2 The exp2 functions (p: 177)
- 7.25 Type-generic math <tgmath.h> (p: 272-273)
- F.10.3.2 The exp2 functions (p: 379)
- 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) |
C++ documentation for exp2
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