erf(), erff(), erfl()

Synopsis:

#include <math.h>

double erf ( double x );

float erff ( float x );

long double erfl ( long double x );

libm

Use the -l m option to qcc to link against this library.

The erf(), erff(), and erfl() functions compute the following:

If x is large and the result of erf() is subtracted from 1.0, the results aren't very accurate; use erfc() instead.

This equality is true: erf(-x) = -erf(x)

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Call feclearexcept(FE_ALL_EXCEPT) before calling erf(), erff(), or erfl().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

The value of the error function.

If `x` is:	These functions return:	Errors:
±0.0	0.0, with the same sign as `x`	—
A value that would cause underflow	`x`	FE_UNDERFLOW
±Inf	1.0, with the same sign as `x`	—
NaN	NaN	—

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.