C++ Math logb

The function computes the logarithm of a given number, using FLT_RADX as base for the logarithm.

Generally, FLT_RADX is equal to 2. Therefore, logb is equivalent to log2.

Syntax

Suppose a number is 'x'. Syntax would be:

float logb(float x);
double logb(double x);
long double logb(long double x);
double logb(integral x);

Parameter

x : The value whose logarithm is to be calculated.

Return value

It returns base FLT_RADX logarithm of x.

If x is zero, then it may cause domain or pole error depending on the library implementation.

Example 1

Let's see the simple example when the value of x is integer type.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     int x=6;
     std::cout << "Value of x is :" <<x<< std::endl;
     cout<<"logarithm value of x is:"<<logb(x);
     return 0;
}

Output:

Value of x is :6
logarithm value of x is:2

In this example, the value of x is 6. The logb function computes the logarithm of x base FLT_RADX.

Example 2

Let's see the simple example when the value of x is float type.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     float x=10.4;
     std::cout << "Value of x is :" <<x<< std::endl;
     cout<<"logarithm value of x is:"<<logb(x);
     return 0;
}

Output:

Value of x is :10.4
logarithm value of x is:3

In this example, the value of x is 10.4. The logb function computes the logarithm of x base FLT_RADX.

Example 3

Let's see the simple example when the value of x is zero.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     int x=0;
     std::cout << "Value of x is  :" <<x<< std::endl;
     cout<<"logarithm value of x is : "<<logb(x);
     return 0;
}

Output:

Value of x is  :0
logarithm value of x is : -inf