lily-library.scm: add `interval-intersection' procedure

diff --git a/scm/lily-library.scm b/scm/lily-library.scm
index 80bc5191bbad43d25f83c239b3b52ed254d466ab..7d0cb126020f916d61284dc497b6b721b2647a5b 100644 (file)
--- a/scm/lily-library.scm
+++ b/scm/lily-library.scm
@@ -455,6 +455,10 @@ found."
    (cons (min (car i1) (car i2))
         (max (cdr i1) (cdr i2))))
 
+(define-public (interval-intersection i1 i2)
+   (cons (max (car i1) (car i2))
+        (min (cdr i1) (cdr i2))))
+
 (define-public (interval-sane? i)
   (not (or  (nan? (car i))
            (inf? (car i))