Fix p/g mixup that I just put back.

[octave.git] / optimization / step_length_positive_definite.m

diff --git a/optimization/step_length_positive_definite.m b/optimization/step_length_positive_definite.m
index 7e15a46513e7333a63f060385f353720745dbc29..255efbac78fd2df4fbc4704fc379e87f624ad77e 100644 (file)
--- a/optimization/step_length_positive_definite.m
+++ b/optimization/step_length_positive_definite.m
@@ -34,10 +34,11 @@ function alpha = step_length_positive_definite(g, Q, p)
   %
   denom = (p' * Q * p);
 
-  if (abs(denom) < eps)
+  % denom is non-negative, since it's a Q-norm. No need to abs() it.
+  if (denom < eps)
     % Catch divide-by-zeros. If denom is effectively zero, set it to
     % something tiny instead. This trick is also used in the PCGM.
-    denom = sign(denom)*eps;
+    denom = eps;
   end
 
   alpha = -(g' * p)/denom;