NAME

erf erfc — error and complementary error functions

SYNOPSIS

#include <math.h>

double erf(double x);
double erfc(double x);

DESCRIPTION

The erf() function computes the error function of x , defined as:

The erfc() function computes 1.0 - erf (x)

An application wishing to check for error situations should set errno to 0 before calling erf(). If errno is non-zero on return, or the return value is NaN, an error has occurred.

RETURN VALUE

Upon successful completion, erf() and erfc() return the value of the error function and complementary error function, respectively.

If x is NaN, NaN is returned and errno may be set to [EDOM].

If the correct value would cause underflow, 0 is returned and errno may be set to [ERANGE].

ERRORS

The erf() and erfc() functions may fail if:

[EDOM]

The value of x is NaN.

[ERANGE]

The result underflows.

No other errors will occur.

EXAMPLES

None.

APPLICATION 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.

FUTURE DIRECTIONS

None.

SEE ALSO

isnan(3) , <math.h> .

DERIVATION

Derived from Issue 1 of the SVID.