NAME¶

std::exp(std::valarray) - std::exp(std::valarray)

Synopsis¶

Defined in header <valarray>
template< class T >
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.

Parameters¶

va - value array to apply the operation to

Return value¶

Value array containing e raised by the values in va.

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.

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
}

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)

See also¶

log(std::valarray) applies the function std::log to each element of valarray
(function template)
exp
expf returns e raised to the given power (\({\small e^x}\)e^x)
expl (function)
(C++11)
(C++11)
exp(std::complex) complex base e exponential
(function template)

Hidden category:¶

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