ERF(3M) ERF(3M)
erf, erfc, erfl, erfcl - error function and complementary error function
#include <math.h>
double erf (double x);
double erfc (double x);
long double erfl (long double x);
long double erfcl (long double x);
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.
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.
exp(3M), matherr(3M)
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ERF(3F) ERF(3F)
erf, erfc, derf, derfc, qerf, qerfc - error function and complementary
error function
real*4 r1, r2, erf
real*8 dp1, dp2, derf
real*16 cd1, cd2, qerf
r2 = erf(r1)
dp2 = derf(dp1)
cd2 = qerf(cd1)
real*4 r1, r2, erfc
real*8 dp1, dp2, derfc
real*16 cd1, cd2, qerfc
r2 = erfc(r1)
dp2 = derfc(dp1)
cd2 = qerfc(cd1)
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 these functions.
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.
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ERF(3F) ERF(3F)
SEE ALSO
exp(3M), matherr(3M)
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