std::cos(std::valarray)
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std::valarray
Defined in header
<valarray>
template< class T >
valarray<T> cos( const valarray<T>& va );
valarray<T> cos( const valarray<T>& va );
For each element in va computes cosine of the value of the element.
[edit] Parameters
va
-
value array to apply the operation to
[edit] Return value
Value array containing cosines of the values in va.
[edit] Notes
Unqualified function (cos) is used to perform the computation. If such function is not available, std::cos 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> cos(const valarray<T>& va) { valarray<T> other = va; for (T& i : other) i = cos(i); return other; // proxy object may be returned }
[edit] Example
Run this code
#include <cmath> #include <iomanip> #include <iostream> #include <valarray> void show(const char* title, const std::valarray <float>& data) { const int w{9}; std::cout << std::setw (w) << title << " | "; for (float x : data) std::cout << std::setw (w) << x << " | "; std::cout << '\n'; } int main() { const std::valarray <float> x{.1, .2, .3, .4}; const auto sin = std::sin (x); const auto cos = std::cos (x); const auto z = (sin * sin) + (cos * cos); show("x", x); show("sin(x)", sin); show("cos(x)", cos); show("z", z); }
Output:
x | 0.1 | 0.2 | 0.3 | 0.4 | sin(x) | 0.0998334 | 0.198669 | 0.29552 | 0.389418 | cos(x) | 0.995004 | 0.980067 | 0.955337 | 0.921061 | z | 1 | 1 | 1 | 1 |
[edit] See also
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