std:: tan (std::valarray)

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

Parameters

Return value

Value array containing tangents of the values in va .

Notes

Unqualified function ( tan ) is used to perform the computation. If such function is not available, std:: tan 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.

Possible implementation

template<class T>
valarray<T> tan(const valarray<T>& va)
{
    valarray<T> other = va;
    for (T& i : other)
        i = tan(i);
 
    return other; // proxy object may be returned
}

Example

#include <cmath>
#include <iostream>
#include <valarray>
 
auto show = [](char const* title, const std::valarray<double>& va)
{
    std::cout << title << " :";
    for (auto x : va)
        std::cout << "  " << std::fixed << x;
    std::cout << '\n';
};
 
int main()
{
    const std::valarray<double> x = {.0, .1, .2, .3};
    const std::valarray<double> y = std::tan(x);
    const std::valarray<double> z = std::atan(y);
 
    show("x          ", x);
    show("y = tan(x) ", y);
    show("z = atan(y)", z);
}

x           :  0.000000  0.100000  0.200000  0.300000
y = tan(x)  :  0.000000  0.100335  0.202710  0.309336
z = atan(y) :  0.000000  0.100000  0.200000  0.300000

See also