std::exp(std::valarray)
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std::valarray
Defined in header
<valarray>
template< class T >
valarray<T> exp( const valarray<T>& va );
valarray<T> exp( const valarray<T>& va );
For each element in va computes e raised to the power equal to the value of the element.
[edit] Parameters
va
-
value array to apply the operation to
[edit] Return value
Value array containing e raised by the values in va.
[edit] Notes
Unqualified function (exp) is used to perform the computation. If such function is not available, std::exp is used due to argument-dependent lookup.
The function can be implemented with the return type different from std::valarray . In this case, the replacement type has the following properties:
- All const member functions of std::valarray are provided.
- std::valarray , std::slice_array , std::gslice_array , std::mask_array and std::indirect_array can be constructed from the replacement type.
- For every function taking a const std::valarray <T>& except begin() and end() (since C++11), identical functions taking the replacement types shall be added;
- For every function taking two const std::valarray <T>& arguments, identical functions taking every combination of const std::valarray <T>& and replacement types shall be added.
- The return type does not add more than two levels of template nesting over the most deeply-nested argument type.
[edit] Possible implementation
template<class T> valarray<T> exp(const valarray<T>& va) { valarray<T> other = va; for (T& i : other) i = exp(i); return other; // proxy object may be returned }
[edit] Example
This example demonstrates the Euler's identity eiπ
= -1 and the related exponents.
Run this code
#include <complex> #include <iostream> #include <numbers> #include <valarray> int main() { const double pi = std::numbers::pi ; std::valarray <std::complex <double>> v = { {0, 0}, {0, pi / 2}, {0, pi}, {0, 3 * pi / 2}, {0, 2 * pi} }; std::valarray <std::complex <double>> v2 = std::exp (v); for (std::cout << std::showpos << std::fixed ; auto n : v2) std::cout << n << '\n'; }
Output:
(+1.000000,+0.000000) (+0.000000,+1.000000) (-1.000000,+0.000000) (-0.000000,-1.000000) (+1.000000,-0.000000)
[edit] See also
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