Print fewer cancelling naturals. issue 1701

Print extra natural when a single sharp lowers a double sharp,
 but not when a single sharp raises a flat.

diff --git a/Documentation/notation/pitches.itely b/Documentation/notation/pitches.itely
index f3ab13aec6a118e60a6ea4183844ffe9e851ff7a..c90ae01468a75e770c912d84e94fd03f71e847f8 100644 (file)
--- a/Documentation/notation/pitches.itely
+++ b/Documentation/notation/pitches.itely
@@ -1677,10 +1677,10 @@ musicB = {
 
 This rule corresponds to the common practice in the twentieth
 century.  It omits some extra natural signs, which were
-traditionally prefixed to accidentals that reduce or reverse
-the direction of a previous alteration.  The @code{modern} rule
+traditionally prefixed to a sharp following a double sharp,
+or a flat following a double flat.  The @code{modern} rule
 prints the same accidentals as @code{default}, with
-two exceptions that serve to avoid ambiguity: after temporary
+two additions that serve to avoid ambiguity: after temporary
 accidentals, cancellation marks are printed also in the following
 measure (for notes in the same octave) and, in the same measure,
 for notes in other octaves.  Hence the naturals before

diff --git a/scm/music-functions.scm b/scm/music-functions.scm
index 31b6c8ad3c48d3861b3ffe500b8a1c6d2f627d76..7c52d41846632b8ffda35086e6cdf49b032949ec 100644 (file)
--- a/scm/music-functions.scm
+++ b/scm/music-functions.scm
@@ -1093,8 +1093,8 @@ specifies whether accidentals should be canceled in different octaves."
              (begin
                (set! need-accidental #t)
                (if (and (not (= this-alt 0))
-                        (or (< (abs this-alt) (abs prev-alt))
-                            (< (* prev-alt this-alt) 0)))
+                        (and (< (abs this-alt) (abs prev-alt))
+                            (> (* prev-alt this-alt) 0)))
                    (set! need-restore #t))))))
 
     (cons need-restore need-accidental)))