# C++ Valarray Library - exp Function

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## Description

It returns a valarray object containing the exponential function values of all the elements of x, in the same order.

## Declaration

Following is the declaration for std::exp function.

template<class T> valarray<T> exp (const valarray<T>& x);

### C++11

template<class T> valarray<T> exp (const valarray<T>& x);

## Parameters

x − It is containing elements of a type for which the unary function abs is defined.

## Return Value

It returns a valarray object containing the exponential function values of all the elements of x, in the same order.

## Exceptions

Basic guarantee − if any operation performed on the elements throws an exception.

## Data races

All elements effectively copied are accessed.

## Example

In below example explains about std::exp function.

#include <iostream>
#include <cstddef>
#include <cmath>
#include <valarray>

int main () {
double val[] = {1.0, 2.0, 4.0, 8.0};
std::valarray<double> foo (val,4);

std::valarray<double> bar = exp (foo);

std::cout << "foo:";
for (std::size_t i=0; i<foo.size(); ++i)
std::cout << ' ' << foo[i];
std::cout << '\n';

std::cout << "bar:";
for (std::size_t i=0; i<bar.size(); ++i)
std::cout << ' ' << bar[i];
std::cout << '\n';

return 0;
}

Let us compile and run the above program, this will produce the following result −

foo: 1 2 4 8
bar: 2.71828 7.38906 54.5982 2980.96
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