From f296c9b7aa080acf9edccdb984d058f9a7a92ae1 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Tue, 13 Aug 2002 18:48:54 +0000
Subject: [PATCH] * lily/beam.cc (least_squares): Add comment.

* input/regression/beam-center-slope.ly: Update.
---
 ChangeLog                             |  7 +++---
 input/regression/beam-center-slope.ly | 35 +++++++++++++++++++++++----
 lily/beam.cc                          | 15 ++++++------
 3 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index cea48543e5..5e7b28a31e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,12 +1,13 @@
 2002-08-13  Jan Nieuwenhuizen  <janneke@gnu.org>
 
+	* lily/beam.cc (least_squares): Add comment.
+
+	* input/regression/beam-center-slope.ly: Update.
+
 	* lily/beam-quanting.cc (score_stem_lengths): Revert oops.
 
 	* input/template/melody-chords.ly: New file.
 
-	* lily/beam.cc (least_squares): Fix asymmetry and scary float
-	comparison.
-
 	* lily/stem.cc (calc_stem_info): Move, document, clean up and fix
 	up-to-stem feature.
 
diff --git a/input/regression/beam-center-slope.ly b/input/regression/beam-center-slope.ly
index a472c9d794..ab963774fc 100644
--- a/input/regression/beam-center-slope.ly
+++ b/input/regression/beam-center-slope.ly
@@ -1,13 +1,38 @@
-\version "1.5.68"
 \header{
-  texidoc="Simple beams on middle line should be allowed to have a slope."
+
+    texidoc="Simple beams on middle staffline be allowed to be
+    slightly sloped.  Beams reaching beyond middle line can have
+    bigger slope."
+
 }
+
 \score{
     \notes\relative c'{
-	[b8 c] [c b]
-	[b''8 a] [a b]
+	%%\property Staff.Stem \set #'beamed-lengths = #'(3.50)
+	%% [c8 d]
+	%% [d c]
+	%% r2
+	%% \property Staff.Stem \set #'beamed-lengths = #'(3.26)
+
+        [a8^"small slope" b]
+        [b a]
+
+	[c'' b]
+	[b c]
+	
+	[c,, d]
+	[d c]
+	
+	[a'' g]
+	[g a]
+
+	[c,,^"bigger slope" e]
+	[e c]
+	
+	[a'' f]
+	[f a]
     }
     \paper{
 	linewidth = 0.0
     }
-}
\ No newline at end of file
+}
diff --git a/lily/beam.cc b/lily/beam.cc
index 63700ab163..5f19968e65 100644
--- a/lily/beam.cc
+++ b/lily/beam.cc
@@ -819,13 +819,14 @@ Beam::least_squares (SCM smob)
       Interval chord (Stem::chord_start_y (first_visible_stem (me)),
 		      Stem::chord_start_y (last_visible_stem (me)));
 
-      /* Make simple beam on middle line have small tilt.
-
-         Ideally, this should be handled by a scoring rule, but that's
-	 complicated because we take stem-info.ideal for determining
-	 beam slopes. */
-      if ((abs (ideal[LEFT]) < 0.5 || abs (ideal[RIGHT]) < 0.5)
-	  && chord.delta () && count == 2)
+      /* Simple beams (2 stems) on middle line should be allowed to be
+	 slightly sloped.
+	 
+	 However, if both stems reach middle line,
+	 ideal[LEFT] == ideal[RIGHT] and ideal.delta () == 0.
+
+	 For that case, we apply artificial slope */
+      if (!ideal[LEFT] && chord.delta () && count == 2)
 	{
 	  /* FIXME. -> UP */
 	  Direction d = (Direction) (sign (chord.delta ()) * UP);
-- 
2.39.2