Defined in header <cmath> | ||
|---|---|---|
float exp2 ( float n ); float exp2f( float n ); | (1) | (since C++11) |
double exp2 ( double n ); | (2) | (since C++11) |
long double exp2 ( long double n ); long double exp2l( long double n ); | (3) | (since C++11) |
double exp2 ( IntegralType n ); | (4) | (since C++11) |
n
double).| n | - | value of floating-point or Integral type |
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.
Errors are reported as specified in math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
#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 raised|
(C++11)(C++11) | returns e raised to the given power (ex) (function) |
|
(C++11)(C++11)(C++11) | returns e raised to the given power, minus one (ex-1) (function) |
|
(C++11)(C++11)(C++11) | base 2 logarithm of the given number (log2(x)) (function) |
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