Avoid NaN with springs of zero length.

diff --git a/lily/simple-spacer.cc b/lily/simple-spacer.cc
index 9129361cbd86702f3524bedec164a49aac27eee9..4da2ac9a87d3439893e93f57dc951b82dc4d6458 100644 (file)
--- a/lily/simple-spacer.cc
+++ b/lily/simple-spacer.cc
@@ -105,7 +105,12 @@ Simple_spacer::add_rod (int l, int r, Real dist)
       Real spring_dist = range_ideal_len (l, r);
       if (spring_dist < dist)
        for (int i = l; i < r; i++)
-         springs_[i].set_distance (springs_[i].distance () * dist / spring_dist);
+         {
+           if (spring_dist)
+             springs_[i].set_distance (springs_[i].distance () * dist / spring_dist);
+           else
+             springs_[i].set_distance (dist / (r - l));
+         }
 
       return;
     }