### erf - erfc -- Calculate Error Functions

Format

>     #include <math.h>
>     double erf(double x);
>     double erfc(double x);

Language Level: XPG4
erf calculates the error function of

erfc computes the value of 1.0 - erf(x). erfc is used in place of erf for large values of x.

Return Value
erf returns a double value that represents the error function. erfc returns a double value representing 1.0 - erf.

Example
This example uses erf and erfc to compute the error function of two numbers.

    #include <stdio.h>
    #include <math.h>

    double smallx, largex, value;

    int main(void)
    {
       smallx = 0.1;
       largex = 10.0;

       value = erf(smallx);         /* value = 0.112463 */
       printf("Error value for 0.1: %lf\n", value);

       value = erfc(largex);        /* value = 2.088488e-45 */
       printf("Error value for 10.0: %le\n", value);
       return 0;

       /*******************************************************
          The output should be:

          Error value for 0.1: 0.112463
          Error value for 10.0:2.088488e-45
       *******************************************************/
    }

Bessel Functions -- Solve Differential Equations
gamma -- Gamma Function
<math.h>