freebsd-dev/lib/msun/man/erf.3
Steve Kargl 3b5e0d0f96 * Makefile:
. Add s_erfl.c to building libm.
  . Add MLINKS for erfl.3 and erfcl.3.

* Symbol.map:
  . Move erfl and erfcl to their proper location.

* ld128/s_erfl.c:
  . Implementations of erfl and erfcl in the IEEE 754 128-bit format.

* ld80/s_erfl.c:
  . Implementations of erfl and erfcl in the Intel 80-bit format.

* man/erf.3:
  . Document the new functions.
  . While here, remove an incomplete sentence.

* src/imprecise.c:
  . Remove the stupidity of mapping erfl and erfcl to erf and erfc.

* src/math.h:
  . Move the declarations of erfl and erfcl to their proper place.

* src/s_erf.c:
  . For architectures where double and long double are the same
    floating point format, use weak references to map erfl to
    erf and ercl to erfc.

Reviewed by:	bde (many earlier versions)
2014-07-13 17:05:03 +00:00

99 lines
2.7 KiB
Groff

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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" from: @(#)erf.3 6.4 (Berkeley) 4/20/91
.\" $FreeBSD$
.\"
.Dd July 13, 2014
.Dt ERF 3
.Os
.Sh NAME
.Nm erf ,
.Nm erff ,
.Nm erfl ,
.Nm erfc ,
.Nm erfcf ,
.Nm erfcl
.Nd error function operators
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn erf "double x"
.Ft float
.Fn erff "float x"
.Ft "long double"
.Fn erfl "long double x"
.Ft double
.Fn erfc "double x"
.Ft float
.Fn erfcf "float x"
.Ft "long double"
.Fn erfcl "long double x"
.Sh DESCRIPTION
These functions calculate the error function of
.Fa x .
.Pp
The
.Fn erf ,
.Fn erff ,
and
.Fn erfl
functions calculate the error function of x; where
.Bd -ragged -offset indent
.if n \{\
erf(x) = 2/sqrt(pi)\(**\|integral from 0 to x of exp(\-t\(**t) dt.
\}
.if t \{\
erf\|(x) :=
(2/\(sr\(*p)\|\(is\d\s8\z0\s10\u\u\s8x\s10\d\|exp(\-t\u\s82\s10\d)\|dt.
\}
.Ed
.Pp
The
.Fn erfc ,
.Fn erfcf ,
and
.Fn erfcl
functions calculate the complementary error function of
.Fa x ;
that is
.Fn erfc
subtracts the result of the error function
.Fn erf x
from 1.0.
.Sh SEE ALSO
.Xr math 3
.Sh HISTORY
The
.Fn erf
and
.Fn erfc
functions appeared in
.Bx 4.3 .