C++ log2Function usage and example

C++ Library Function <cmath>

C ++in log2function returns the logarithm of the parameter2logarithm to the base.

The function returns<cmath>defined in the header file.

log2x = log2(x)

log2function prototype [from C ++ 11Standard library begins]

double log2(double x);
float log2(float x);
long double log2(long double x);
double log2(T x);　//for integer

LOG2function has only one parameter and returns a value of type double, float, or long double.

log2parameter

log2function uses the range[0, ∞]is a single required parameter.
If the value is less than zero, then log2function returns NaN (Not a Number).

log2Returns

log2function returns the logarithm of the number with2logarithm to the base.

Example1: C2in log2How does the function work?

#include　<iostream>
#include　<cmath>
using　namespace　std;
int　main　()
{
　　　　double x =　13.056, result;
　　　　result　=　log2(x);
　　　　cout　<<　"log2(x) = " << result << endl;
　　　　x =　-3.591;
　　　　result　=　log2(x);
　　　　cout　<<　"log2(x) = " << result << endl;
　　　　
　　　　return　0;
}

The output when running the program is:

log2(x) =　3.70664
log2(x) = nan

Example2: with integer type log2function

#include　<iostream>
#include　<cmath>
using　namespace　std;
int　main　()
{
　　　　double　result;
　　　　int　x　=　2201;
　　　　result　=　log2(x);
　　　　cout　<<　"log2("　<<　x　<<　")　=　"　<<　result　<<　endl;
　　　　return　0;
}

The output when running the program is:

log2(2201)　=　11.1039

C++ Library Function <cmath>