springs: comment and typo

diff --git a/lily/spring.cc b/lily/spring.cc
index 312b2ed00f49644598966832b50d1598396eae3b..ec8240b84d09f4899547bc787b7be73fa1bfa2b4 100644 (file)
--- a/lily/spring.cc
+++ b/lily/spring.cc
@@ -17,6 +17,23 @@
   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+/*
+  Springs help chains of objects, such as the notes in a line of music,
+  distribute themselves evenly.
+  Each spring decides the length from the reference point of one object
+  along the line to the reference point of the next, based on a force
+  applied to the entire chain (see Spring::length() for details):
+     length = distance_ + flexibility * force
+
+  distance_  is the ideal separation between reference points
+  inverse_stretch_strength_ is the flexibility when the force is stretching
+  inverse_compress_strength_ is the flexibility when the force is compressing
+  min_distance_ sets a lower limit on length
+
+  Typically, the force applied to a list of objects ranges from about
+  -1 to about 1, though there are no set limits.
+*/
+
 #include "spring.hh"
 
 Spring::Spring ()
@@ -69,7 +86,7 @@ Spring::operator *= (Real r)
 {
   distance_ = max (min_distance_, distance_ * r);
   inverse_compress_strength_ = max (0.0, distance_ - min_distance_);
-  inverse_stretch_strength_ *= 0.8;
+  inverse_stretch_strength_ *= r;
   update_blocking_force ();
 }