erfc(3) [netbsd man page]

```ERF(3)							   BSD Library Functions Manual 						    ERF(3)

NAME
erf, erff, erfc, erfcf -- error function operators

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

double
erf(double x);

float
erff(float x);

double
erfc(double x);

float
erfcf(float x);

DESCRIPTION
These functions calculate the error function of x.

The erf() calculates the error function of x; where

erf(x) = 2/sqrt(pi)*integral from 0 to x of exp(-t*t) dt.

The erfc() function calculates the complementary error function of x; that is erfc() subtracts the result of the error function erf(x) from
1.0.  This is useful, since for large x places disappear.

math(3)

HISTORY
The erf() and erfc() functions appeared in 4.3BSD.

BSD								  April 20, 1991							       BSD```

Check Out this Related Man Page

```erfc(3M)						  Mathematical Library Functions						  erfc(3M)

NAME
erfc, erfcf, erfcl - complementary error function

SYNOPSIS
cc [ flag... ] file... -lm [ library... ]
#include <math.h>

double erfc(double x);

float erfcf(float x);

long double erfcl(long double x);

DESCRIPTION
These function compute the complementary error function 1.0 - erf(x).

RETURN VALUES
Upon successful completion, these functions return the value of the complementary error function.

If x is NaN, a NaN is returned.

If x is +-0, +1 is returned.

If x is -Inf, +2 is returned.

If x is +Inf, 0 is returned.

ERRORS
No errors are defined.

USAGE
The  erfc() function is provided because of the extreme loss of relative accuracy if erf(x) is called for large x and the result subtracted
from 1.0.

ATTRIBUTES
See attributes(5) for descriptions of the following attributes:

+-----------------------------+-----------------------------+
|      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
+-----------------------------+-----------------------------+
|Interface Stability	     |Standard			   |
+-----------------------------+-----------------------------+
|MT-Level		     |MT-Safe			   |
+-----------------------------+-----------------------------+