std::abs(std::valarray)
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std::valarray
Defined in header
<valarray>
template< class T >
valarray<T> abs( const valarray<T>& va );
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.
- 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.
[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
Run this code
#include <iostream> #include <valarray> 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
[edit] See also
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