< cpp‎ | numeric‎ | valarray
Defined in header <valarray>
template< class T >
valarray<T> abs( const valarray<T>& va );

Computes absolute value of each element in the value array.


[edit] Parameters

va - value array to apply the operation to

[edit] Return value

Value array containing absolute values of the values in va.

[edit] Notes

Unqualified function (abs) is used to perform the computation. If such function is not available, std::abs 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++14) 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.

[edit] Possible implementation

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

[edit] Example

#include <valarray>
#include <iostream>
int main()
    std::valarray<int> v{1, -2, 3, -4, 5, -6, 7, -8};
    std::valarray<int> v2 = std::abs(v);
    for(auto n : v2) {
        std::cout << n << ' ';
    std::cout << '\n';


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[edit] See also

computes absolute value of an integral value (|x|)
absolute value of a floating point value (|x|)
returns the magnitude of a complex number
(function template)