std::exp2,std::exp2f,std::exp2l (3) - Linux Manuals

std::exp2,std::exp2f,std::exp2l: std::exp2,std::exp2f,std::exp2l

NAME

std::exp2,std::exp2f,std::exp2l - std::exp2,std::exp2f,std::exp2l

Synopsis

Defined in header <cmath>
float exp2 ( float n ); (1) (since C++11)
float exp2f( float n );
double exp2 ( double n ); (2) (since C++11)
long double exp2 ( long double n ); (3) (since C++11)
long double exp2l( long double n );
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