valarray log() function in C++

The log() function is defined in valarray header file. This function is used to calculate natural logarithm of the value of the elements in valarray.
Syntax:

log(varr);

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

Returns: This function returns a valarray containing the natural logarithm of all the elements.

Below programs illustrate the above function:

Example 1:-

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

#include<bits/stdc++.h>
using namespace std;
int main()
{
    // Initializing valarray
    valarray<double>
 varr = { 1, 2, 3, 4, 5 };

    // Declaring new valarray
    valarray<double> varr1 ;

    // use of log() function
    varr1 = log(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 0.693147 1.09861 1.38629 1.60944

Example 2:-

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

#include<bits/stdc++.h>
using namespace std;
int main()
{
    // Initializing valarray
    valarray<double>
 varr = { -1, 6, 3, 45, 5 };

    // Declaring new valarray
    valarray<double> varr1 ;

    // use of log() function
    varr1 = log(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 : 
nan 1.79176 1.09861 3.80666 1.60944