For exceptional cases of mathematical formulae that can't reasonably

be represented otherwise, use eqn(7).
Idea originally from bentley@, feedback and OK bentley@, OK tb@,
and no objection from jmc@.

2 files changed, 23 insertions, 18 deletions

diff --git a/lib/libm/man/erf.3 b/lib/libm/man/erf.3
index bb1cba2070a..a3d2bb37b37 100644
--- a/lib/libm/man/erf.3
+++ b/lib/libm/man/erf.3
@@ -1,4 +1,5 @@
-.\"	$OpenBSD: erf.3,v 1.15 2016/04/26 19:49:22 tb Exp $
+'\" e
+.\"	$OpenBSD: erf.3,v 1.16 2017/08/26 17:04:28 schwarze Exp $
 .\" Copyright (c) 1985, 1991 Regents of the University of California.
 .\" All rights reserved.
 .\"
@@ -28,7 +29,7 @@
 .\"
 .\"     from: @(#)erf.3	6.4 (Berkeley) 4/20/91
 .\"
-.Dd $Mdocdate: April 26 2016 $
+.Dd $Mdocdate: August 26 2017 $
 .Dt ERFC 3
 .Os
 .Sh NAME
@@ -59,7 +60,7 @@ These functions calculate the error function of
 .Pp
 The
 .Fn erf
-calculates the error function of x, and
+function calculates the error function of x, and
 the
 .Fn erff
 and
@@ -67,12 +68,11 @@ and
 functions are single and double precision versions of
 .Fn erf .
 The error function is defined as:
-.Bd -filled -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 pi)\|\(is\d\s8\z0\s10\u\u\s8x\s10\d\|exp(\-t\u\s82\s10\d)\|dt. \}
+.Bd -unfilled -offset indent
+.EQ
+roman erf left ( x right ) =
+2 over sqrt pi int from 0 to x e sup {- t sup 2} dt
+.EN
 .Ed
 .Pp
 The
diff --git a/lib/libm/man/lgamma.3 b/lib/libm/man/lgamma.3
index 8aab5564140..136b8ed5e1e 100644
--- a/lib/libm/man/lgamma.3
+++ b/lib/libm/man/lgamma.3
@@ -1,4 +1,5 @@
-.\"	$OpenBSD: lgamma.3,v 1.27 2016/04/26 19:49:22 tb Exp $
+'\" e
+.\"	$OpenBSD: lgamma.3,v 1.28 2017/08/26 17:04:28 schwarze Exp $
 .\" Copyright (c) 1985, 1991 Regents of the University of California.
 .\" All rights reserved.
 .\"
@@ -28,7 +29,7 @@
 .\"
 .\"     from: @(#)lgamma.3	6.6 (Berkeley) 12/3/92
 .\"
-.Dd $Mdocdate: April 26 2016 $
+.Dd $Mdocdate: August 26 2017 $
 .Dt LGAMMA 3
 .Os
 .Sh NAME
@@ -67,16 +68,20 @@
 .Fn tgammal "long double x"
 .Sh DESCRIPTION
 .Fn lgamma x
-.if t \{\
 returns ln\||\(*G(x)| where
-.Bd -unfilled -offset indent
-\(*G(x) = \(is\d\s8\z0\s10\u\u\s8\(if\s10\d t\u\s8x\-1\s10\d e\u\s8\-t\s10\d dt	for x > 0 and
+.Bd -filled -offset indent
+.EQ
+GAMMA left ( x right ) =
+int from 0 to inf t sup {x - 1} e sup -t dt
+.EN
+\ \ \ for x > 0 and
 .br
-\(*G(x) = \(*p/(\(*G(1\-x)\|sin(\(*px))	for x < 1.
+.EQ
+GAMMA left ( x right ) =
+pi over { GAMMA left ( 1 - x right ) sin left ( pi x right ) }
+.EN
+\ \ \ for x < 1.
 .Ed
-.\}
-.if n \
-returns ln\||\(*G(x)|.
 .Pp
 The external integer
 .Va signgam