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std::cos(std::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.

Parameters

va - value array to apply the operation to

Return value

Value array containing cosines of the values in va.

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:

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
}

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 |

See also

applies the function std::sin to each element of valarray
(function template)
applies the function std::tan to each element of valarray
(function template)
applies the function std::acos to each element of valarray
(function template)
(C++11)(C++11)
computes cosine (\({\small\cos{x} }\)cos(x))
(function)
computes cosine of a complex number (\({\small\cos{z} }\)cos(z))
(function template)

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