ERF(3M)ERF(3M)NAME
erf, erfc, erfl, erfcl - error function and complementary error function
SYNOPSIS
#include <math.h>
double erf (double x);
double erfc (double x);
long double erfl (long double x);
long double erfcl (long double x);
DESCRIPTION
erf returns the error function of x, defined as
(2 / sqrt(pi)) integral{0 to x} of (e ** -t **2) dt.
erfc, which returns 1.0 - erf(x), 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 (e.g., for x = 10, 12 places are lost).
The standard math library libm.a, libmx.a, and libm43.a each contain
versions of erf and erfc, however the long double-precision routines erfl
and erfcl are only available in the standard math library, -lm, and in
-lmx.
DIAGNOSTICS
In the diagnostics below, functions in the standard math library libm.a,
are referred to as -lm versions, those in math library libmx.a are
referred to as -lmx versions, and those in the the BSD math library
libm43.a are referred to as -lm43 versions. The -lm and -lmx versions
always return the default Quiet NaN and set errno to EDOM when a NaN is
used as an argument. A NaN argument usually causes the -lm43 versions to
return the same argument. The -lm43 versions never set errno.
See matherr(3M) for a description of error handling for -lmx functions.
SEE ALSOexp(3M), matherr(3M)
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