std::exp(std::valarray)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Numerics library

Common mathematical functions
Mathematical special functions (C++17)
Mathematical constants (C++20)
Basic linear algebra algorithms (C++26)
Floating-point environment (C++11)
Complex numbers
Numeric array (valarray)
Pseudo-random number generation
Factor operations
gcd (C++17)	lcm (C++17)
Interpolations
midpoint (C++20)	lerp (C++20)
Saturation arithmetic
add_sat (C++26) sub_sat (C++26) saturate_cast (C++26)	mul_sat (C++26) div_sat (C++26)
Generic numeric operations
iota (C++11) ranges::iota (C++23) accumulate inner_product adjacent_difference partial_sum	reduce (C++17) transform_reduce (C++17) inclusive_scan (C++17) exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
Bit operations
has_single_bit (C++20)     bit_cast (C++20) bit_ceil (C++20) bit_floor (C++20) bit_width (C++20) rotl (C++20) rotr (C++20)	popcount (C++20) countl_zero (C++20) countl_one (C++20) countr_zero (C++20) countr_one (C++20) byteswap (C++23) endian (C++20)

 

std::valarray

Member functions
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>>=
Non-member functions
swap(std::valarray) (C++11) begin(std::valarray) (C++11)   end(std::valarray) (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>=
Helper classes
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.
• 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)
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)