[lisplab-cvs] r103 - src/matrix

[Jørn Inge Vestgården]

Author: jivestgarden
Date: Fri Oct 16 14:53:31 2009
New Revision: 103

Log:
minor fixes

Modified:
   src/matrix/level1-sparse.lisp

Modified: src/matrix/level1-sparse.lisp
==============================================================================
--- src/matrix/level1-sparse.lisp	(original)
+++ src/matrix/level1-sparse.lisp	Fri Oct 16 14:53:31 2009
@@ -17,10 +17,10 @@
 ;;; with this program; if not, write to the Free Software Foundation, Inc.,
 ;;; 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
-;;; Note that there is probably not much to save using this on most operations 
+;;; Purpose of the sparse matrices is to save space. 
+;;; Currently you won't save much time on most operations 
 ;;; since they by default go through all elements. 
 
-
 (in-package :lisplab)
 
 (defclass matrix-sparse
@@ -39,11 +39,13 @@
   (with-slots (rows cols size hash-store default-element ) m
     (setf size (* rows cols))
     (unless hash-store
-      (setf hash-store (make-hash-table :test 'eq)))
+      ;; Uses eq as test. It should be safe since the keys are matrix indices 
+      ;; and they should be fixnum (or fixnum size) on most platforms. 
+      (setf hash-store (make-hash-table :test 'eq))) 
     (unless default-element
       (setf default-element value))))
 
-;;; Add clases to the description system
+;;; Adds classes to the description system
 (add-matrix-class 'matrix-sparse :any :sparse :any)
 
 (defmethod mref ((matrix matrix-sparse) row col)
@@ -55,9 +57,11 @@
 	(slot-value matrix 'default-element))))
 
 (defmethod (setf mref) (value (matrix  matrix-sparse) row col)
-  (setf (gethash (column-major-idx row col (slot-value matrix 'rows))
-		 (slot-value matrix 'hash-store))
-	value))
+  (if (eql value (slot-value matrix 'default-element))
+      value
+      (setf (gethash (column-major-idx row col (slot-value matrix 'rows))
+		     (slot-value matrix 'hash-store))
+	    value)))
   
 (defmethod vref ((matrix  matrix-sparse) idx)
  (multiple-value-bind (val ok)