| Defined in header <cmath> | ||
|---|---|---|
double exp2( double n ); | (1) | (since C++11) |
float exp2( float n ); | (2) | (since C++11) |
long double exp2( long double n ); | (3) | (since C++11) |
double exp2( Integral n ); | (4) | (since C++11) |
1-3) Computes 2 raised to the given power
n 4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2) (the argument is cast to
double).Parameters
| n | - | value of floating-point or Integral type |
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 <iostream>
#include <cmath>
#include <cerrno>
#include <cstring>
#include <cfenv>
#pragma STDC FENV_ACCESS ON
int main()
{
std::cout << "exp2(4) = " << std::exp2(4) << '\n'
<< "exp2(0.5) = " << std::exp2(0.5) << '\n'
<< "exp2(-4) = " << std::exp2(-4) << '\n';
// special values
std::cout << "exp2(-0) = " << std::exp2(-0.0) << '\n'
<< "exp2(-Inf) = " << std::exp2(-INFINITY) << '\n';
// error handling
errno=0; std::feclearexcept(FE_ALL_EXCEPT);
std::cout << "exp2(1024) = " << std::exp2(1024) << '\n';
if(errno == ERANGE)
std::cout << " errno == ERANGE: " << std::strerror(errno) << '\n';
if(std::fetestexcept(FE_OVERFLOW))
std::cout << " FE_OVERFLOW raised\n";
}Possible output:
exp2(4) = 16
exp2(0.5) = 1.41421
exp2(-4) = 0.0625
exp2(-0) = 1
exp2(-Inf) = 0
exp2(1024) = inf
errno == ERANGE: Numerical result out of range
FE_OVERFLOW raisedSee also
| returns e raised to the given power (ex) (function) | |
| (C++11) | returns e raised to the given power, minus one (ex-1) (function) |
| (C++11) | base 2 logarithm of the given number (log2(x)) (function) |
C documentation for exp2 | |
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