log2() function in C++ with examples
By Karandeep SinghHey, guys today we are going to learn about log2() function in C++. It is a mathematical function which returns the value of logarithmic base 2 value of the argument passed. Header file for log2() function in C++ is <math.h> also known as <cmath>.Its syntax is :
log2(x)
log2() function accepts argument (x) value in the range of Zero to infinity i.e Its domain is [0,∞]. log2() returns nan which means ‘Not a Number’ when an argument with a negative value is passed to the function. log2() function has return types ‘float’, ‘double’ and ‘long double’ it returns the logarithmic value as ‘float’ , ‘double’ and ‘long double’ as shown:
float y = log2(x)//x is of float datatype double y = log2(x)//x is of double datatype long double y = log2(x)//x is of long double datatype
Please note that ‘double’ datatype is used to return the logarithmic base 2 value of the integer values i.e when the argument (x) is of integer datatype
as shown:
double y = log2(x)//x is of integer datatype
log2() function return the base 2 logarithmic values as:
If x<0, log2() will return nan i.e(Not a Number).
x=0, log2() will return negative infinity i.e(-∞).
If 0<x<1, log2() will return negative value.
If x=1, log2() will return Zero i.e(0).
If x>1, log2() will return positive value.
Using log2() function in C++ by passing the argument(x) of different datatypes
#include <iostream>
#include <math.h>
using namespace std;
int main()
{
int x=64;
float x1=15.092;
double x2=90.1567834;
long double x3=121.1309151313;
cout<<"value of log base 2(x)="<<log2(x)<<endl;
cout<<"value of log base 2(x1)="<<log2(x1)<<endl;
cout<<"value of log base 2(x2)="<<log2(x2)<<endl;
cout<<"value of log base 2(x3)="<<log2(x3)<<endl;
return 0;
}Output:
value of log base 2(x)=6 value of log base 2(x1)=3.91571 value of log base 2(x2)=6.49436 value of log base 2(x3)=6.92042
Using log2() to show different output results depending on the value of argument passes (x)
#include <iostream>
#include <math.h>
using namespace std;
int main()
{
float x=-15;
float x1=0;
float x2=0.135;
float x3=1;
float x4=9.15;
cout<<"value of log base 2(-15)="<<log2(x)<<endl;
cout<<"value of log base 2(0)="<<log2(x1)<<endl;
cout<<"value of log base 2(0.135)="<<log2(x2)<<endl;
cout<<"value of log base 2(1)="<<log2(x3)<<endl;
cout<<"value of log base 2(9.15)="<<log2(x4)<<endl;
return 0;
}Output:
value of log base 2(-15)=nan value of log base 2(0)=-inf value of log base 2(0.135)=-2.88897 value of log base 2(1)=0 value of log base 2(9.15)=3.19377
Other logarithmic functions:
- log(): It returns the natural logarithmic of the argument passed.
- log10(): It returns the logarithmic base 10 of the argument passed.
Also, refer
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