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valarray log() Function in C++ with Examples

C++ valarray log() Function: Here, we will learn about the log() function, its usages, syntax and examples.
Submitted by Shivang Yadav, on May 12, 2022

The valarray class in C++ is a special container that is used for holding elements like an array and performing operations on them.

Mathematical Log Value

Log or logarithm is the exponent or power value to which the given base value is raised in order to yield the given number.

For expression,

ba = x
Logbx = a
log b (a) = x => a = ba

C++ STL std::log(std::valarray) Function

The log() function of the valarray class is used to calculate the value of the log of elements of the valarray. It returns a valarray with each element calculated using log() function.

Syntax

template< class T >
valarray<T> log( const valarray<T>& va );

// or
log(valarrayName)

Parameter(s)

It accepts a single parameter which is the original valarray.

Return value

It returns a valarray with the logarithmic value of each element of the original valarray.

Example 1

#include <iostream>
#include <valarray>
using namespace std;

int main()
{
    // Declaring valarray
    valarray<double> myvalarr = { 3, 6, 2, 5, 1 };

    // Printing the elements of valarray
    cout << "The elements of orignal valarray are : ";
    for (double& ele : myvalarr)
        cout << ele << " ";

    // Creating a new valarray
    valarray<double> logValarray;
    logValarray = log(myvalarr);

    cout << "\nThe elements of logarithmic valarray are : ";
    for (double& ele : logValarray)
        cout << ele << " ";

    return 0;
}

Output

The elements of orignal valarray are : 3 6 2 5 1 
The elements of logarithmic valarray are : 1.09861 1.79176 0.693147 1.60944 0

Example 2

#include <iostream>
#include <valarray>
using namespace std;

int main()
{
    // Declaring valarray
    valarray<double> myvalarr = { 3.1, -6, 0.2, 5, 1.7 };

    // Printing the elements of valarray
    cout << "The elements of orignal valarray are : ";
    for (double& ele : myvalarr)
        cout << ele << " ";

    // Creating a new valarray
    valarray<double> logValarray;
    logValarray = log(myvalarr);

    cout << "\nThe elements of logarithmic valarray are : ";
    for (double& ele : logValarray)
        cout << ele << " ";

    return 0;
}

Output

The elements of orignal valarray are : 3.1 -6 0.2 5 1.7 
The elements of logarithmic valarray are : 1.1314 -nan -1.60944 1.60944 0.530628