erfc

Evaluates the real complementary error function erfc(x).

Synopsis

#include <imsl.h>

float imsl_f_erfc (float x)

The type double function is imsl_d_erfc.

Required Arguments

float x (Input)
Point at which the complementary error function is to be evaluated.

Return Value

The value of the complementary error function erfc(x).

Description

The complementary error function erfc(x) is defined to be

 

The argument x must not be so large that the result underflows. Approximately, x should be less than

 

where s is the smallest representable floating-point number.

 

Figure 1,  Plot of erfc(x)

Example

Evaluate the error function at x = 1/2.

 

#include <imsl.h>

#include <stdio.h>

 

int main()

{

float x = 0.5;

float ans;

 

ans = imsl_f_erfc(x);

printf("erfc(%f) = %f\n", x, ans);

}

Output

 

erfc(0.500000) = 0.479500

Alert Errors

IMSL_LARGE_ARG_UNDERFLOW

The argument x is so large that the result underflows.