std::exp2, std::exp2f, std::exp2l
From cppreference.com
Defined in header <cmath>
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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) |
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
Run this code
#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
See also
(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) |