std::atan(std::valarray)
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std::valarray
Defined in header
<valarray>
template< class T >
valarray<T> atan( const valarray<T>& va );
valarray<T> atan( const valarray<T>& va );
For each element in va computes arc tangent of the value of the element.
[edit] Parameters
va
-
value array to apply the operation to
[edit] Return value
Value array containing arc tangents of the values in va.
[edit] Notes
Unqualified function (atan) is used to perform the computation. If such function is not available, std::atan 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> atan(const valarray<T>& va) { valarray<T> other = va; for (T& i : other) i = atan(i); return other; // proxy object may be returned }
[edit] Example
Run this code
#include <algorithm> #include <cmath> #include <iostream> #include <valarray> auto show = [](char const* title, const std::valarray <float>& va) { std::cout << title << " :"; std::for_each (std::begin (va), std::end (va), [](const float x) { std::cout << " " << std::fixed << x; }); std::cout << '\n'; }; int main() { const std::valarray <float> x = {.1f, .3f, .6f, .9f}; const std::valarray <float> f = std::atan (x); const std::valarray <float> g = std::tan (f); show("x ", x); show("f = atan(x)", f); show("g = tan(f) ", g); }
Output:
x : 0.100000 0.300000 0.600000 0.900000 f = atan(x) : 0.099669 0.291457 0.540420 0.732815 g = tan(f) : 0.100000 0.300000 0.600000 0.900000
[edit] See also
(C++11)
(function template) [edit]
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