valarray atan() function in C++

The atan() function is defined in valarray header file. This function is used to calculate arc tangent of the value of each element in valarray and returns a valarray containing the arc tangent of all the elements.

Syntax:

atan(varr);

Parameter: This function takes a mandatory parameter varr which represents valarray.

Returns: This function returns a valarray containing the arc tangent of all the elements.

Below programs illustrate the above function:

Example 1:-

// C++ program to demonstrate
// example of atan() function.

#include <bits/stdc++.h>
using namespace std;

int main()
{
    // Initializing valarray
    valarray<double>
        varr = { 0, 0.25, 0.5, 0.75, 1 };

    // Declaring new valarray
    valarray<double> varr1;

    // use of atan() function
    varr1 = atan(varr);

    // Displaying new elements value
    cout << "The new valarray with"
         << " manipulated values is : "
         << endl;

    for (double& x : varr1) {
        cout << x << " ";
    }

    cout << endl;

    return 0;
}

Output:

The new valarray with manipulated values is : 
0 0.244979 0.463648 0.643501 0.785398

Example 2:-

// C++ program to demonstrate
// example of atan() function.

#include <bits/stdc++.h>
using namespace std;
int main()
{
    // Initializing valarray
    valarray<double>
        varr = { 0.2, 0.14, 5.0, 0.0 };

    // Declaring new valarray
    valarray<double> varr1;

    // use of atan() function
    varr1 = atan(varr);

    // Displaying new elements value
    cout << "The new valarray with"
         << " manipulated values is : "
         << endl;

    for (double& x : varr1) {
        cout << x << " ";
    }

    cout << endl;

    return 0;
}

Output:

The new valarray with manipulated values is : 
0.197396 0.139096 1.3734 0