# std::abs(std::valarray)

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< 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.

### Parameters

va | - | value array to apply the operation to

### Return value

Value array containing absolute values of the values in `va`.

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

### Example

Run this code

    #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';
    }

Output:

    1 2 3 4 5 6 7 8

### See also

abs(int)labs llabs (C++11) | computes absolute value of an integral value (|x|) (function)
abs(float)fabs fabsf fabsl (C++11)(C++11) | absolute value of a floating point value (|x|) (function)
abs(std::complex) | returns the magnitude of a complex number (function template)

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