# std::tan(std::valarray)

< cpp‎ | numeric‎ | valarray
 Defined in header  template< class T > valarray tan( const valarray& va );

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

## Contents

### Parameters

 va - value array to apply the operation to

### 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:

### Possible implementation

 template valarray tan(const valarray& va) { valarray 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);
}

Output:

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