Logged the filtered but not zeroed position.

Change-Id: Ica47de1c6b84fd71540428cba06ac266d2e899fe
diff --git a/frc971/zeroing/zeroing.h b/frc971/zeroing/zeroing.h
index 433745a..5216df0 100644
--- a/frc971/zeroing/zeroing.h
+++ b/frc971/zeroing/zeroing.h
@@ -53,6 +53,10 @@
   // some contexts we refer to this as the "offset".
   double offset() const { return start_pos_; }
 
+  // Return the estimated position of the corresponding mechanism not using the
+  // index pulse, even if one is available.
+  double filtered_position() const { return filtered_position_; }
+
   // Returns a number between 0 and 1 that represents the percentage of the
   // samples being used in the moving average filter. A value of 0.0 means that
   // no samples are being used. A value of 1.0 means that the filter is using
@@ -76,6 +80,8 @@
 
   // The estimated position.
   double pos_;
+  // The unzeroed filtered position.
+  double filtered_position_ = 0.0;
   // The distance between two consecutive index positions.
   double index_diff_;
   // The next position in 'start_pos_samples_' to be used to store the next