function template
<valarray>

std::atan

template<class T> valarray<T> atan (const valarray<T>& x);
Compute arc tangent of valarray elements
Returns a valarray object containing the principal values of the arc tangent of all the elements of x, expressed in radians, in the same order.

The function calls acos (unqualified) once for each element.

This function overloads cmath's atan.

Parameters

x
valarray containing elements of a type for which the unary function atan is defined.

Return value

A valarray object with the arc tangent values of the elements of x.

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
 
// atan valarray example
#include <iostream>     // std::cout
#include <cstddef>      // std::size_t
#include <cmath>        // std::atan(double)
#include <valarray>     // std::valarray(valarray)

int main ()
{
  double val[] = {0.0, 0.25, 0.5, 0.75, 1.0};
  std::valarray<double> foo (val,5);

  std::valarray<double> bar = atan (foo);

  std::cout << "foo:";
  for (std::size_t i=0; i<foo.size(); ++i)
    std::cout << ' ' << foo[i];
  std::cout << '\n';

  std::cout << "bar:";
  for (std::size_t i=0; i<bar.size(); ++i)
    std::cout << ' ' << bar[i];
  std::cout << '\n';

  return 0;
}


Output:

foo: 0 0.25 0.5 0.75 1
bar: 0 0.244979 0.463648 0.643501 0.785398

See also

atan (cmath)
Compute arc tangent (function )
atan2
Compute atan2 of valarray elements (function template )
tan
Compute tangent of valarray elements (function template )