C++ Math erfc()

The erfc() function computes the complementary error function value of a parameter passed to the function.

Suppose a number is 'x':

Syntax

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

Parameter

x: It is a floating point value.

Return value

It returns the complementary error function value of x.

Parameter	Return value
x=+∞	+0
x= -∞	2
x=nan	nan

Example 1

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

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     float x= 2.0/0.0;
     cout<<"Value of x is : "<<x<<'\n';
     cout<<"erfc(x) : "<<erfc(x);
     return 0;
}

Output:

Value of x is : inf
erfc(x) : 0

In the above example, the value of x is positive infinite. Therefore, the function erfc() returns 0 value.

Example 2

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

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     float x= -1.0/0.0;
     cout<<"Value of x is : "<<x<<'\n';
     cout<<"erfc(x) : "<<erfc(x);
     return 0;
}

Output:

Value of x is : -inf
erfc(x) : 2

In the above example, the value of x is negative infinite. Therefore, the function erfc() returns 2.

Example 3

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

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     float x= sqrt(-2);
     cout<<"Value of x is : "<<x<<'\n';
     cout<<"erfc(x) : "<<erfc(x);
     return 0;
}

Output: