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std::cos(std::valarray)

From cppreference.com
< cpp‎ | numeric‎ | valarray
 
 
 
 
Defined in header <valarray>
template< class T >
valarray<T> cos( const valarray<T>& va );

For each element in va computes cosine of the value of the element.

Contents

[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:

[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;
}

[edit] Example

#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

applies the function std::sin to each element of valarray
(function template) [edit]
applies the function std::tan to each element of valarray
(function template) [edit]
applies the function std::acos to each element of valarray
(function template) [edit]
(C++11)(C++11)
computes cosine (cos(x))
(function) [edit]
computes cosine of a complex number (cos(z))
(function template) [edit]