std::exp(std::valarray)

< cpp‎ | numeric‎ | valarray

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 Defined in header `` template< class T > valarray exp( const valarray& 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:

Possible implementation

 ```template< class T > valarray exp( const valarray& va ) { valarray other = va; for (T &i : other) { i = exp(i); } return other; // proxy object may be returned }```

Example

This example demonstrates the Euler's identity e
= -1
and the related exponents.

```#include <iostream>
#include <complex>
#include <valarray>

int main()
{
const double pi = std::acos(-1);
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(auto n : v2) {
std::cout << std::fixed << n << '\n';
}
}```

Output:

```(1.000000,0.000000)
(0.000000,1.000000)
(-1.000000,0.000000)
(-0.000000,-1.000000)
(1.000000,-0.000000)```