std::exp(std::valarray)

 

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std::valarray

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valarray::valarray valarray::~valarray valarray::operator= valarray::operator[]   valarray::swap valarray::size valarray::resize valarray::sum valarray::min valarray::max valarray::shift valarray::cshift valarray::apply	valarray::operator+valarray::operator-valarray::operator~valarray::operator! valarray::operator+=valarray::operator-=valarray::operator*=valarray::operator/=valarray::operator%=valarray::operator&=valarray::operator|=valarray::operator^=valarray::operator<<=valarray::operator>>=
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swap (C++11) begin (C++11) end (C++11) abs exp log log10 pow sqrt sin cos tan asin acos atan atan2 sinh cosh tanh	operator*operator/operator%operator+operator-operator^operator&operator|operator<<operator>>operator&&operator|| operator==operator!=operator<operator>operator<=operator>=
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slice_array gslice_array indirect_array	slice gslice mask_array
Deduction guides(C++17)

 

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.
• All functions accepting an argument of type const std::valarray& except begin() and end() (since C++11) should also accept the replacement type.
• All functions accepting two arguments of type const std::valarray& should accept every combination of const std::valarray& and the replacement type.
• 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 <iostream>
#include <complex>
#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)
expexpfexpl (C++11)(C++11)	returns e raised to the given power (\({\small e^x}\)ex) (function)
exp(std::complex)	complex base e exponential (function template)