# 3.5.3.1.8 Erfc

## Definition:

$erfc = erfc(x)$ calculates an approximate value for the complement of the error function

$erfc(x)=\frac 1{\sqrt{\pi }}\int_x^\infty e^{\frac{-u^2}2}du=1-{erf(x)}$

The approximation is based on a Chebyshev expansion.

For more information please review the s15adc function in the NAG document.

## Parameters:

x (input, double)
The argument x of the function.
erfc (output, double)
Approximate value of the complement of the error function.