changeset 10536:74cb77f0a163

update NEWS
author Jaroslav Hajek <highegg@gmail.com>
date Tue, 20 Apr 2010 09:03:26 +0200
parents 3f973f6c841c
children fdf28dae0f37
files ChangeLog NEWS
diffstat 2 files changed, 24 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- a/ChangeLog	Tue Apr 20 08:42:03 2010 +0200
+++ b/ChangeLog	Tue Apr 20 09:03:26 2010 +0200
@@ -1,3 +1,7 @@
+2010-04-20  Jaroslav Hajek  <highegg@gmail.com>
+
+	* NEWS: Update.
+
 2010-04-16  David Bateman  <dbateman@free.fr>
 
 	* PROJECTS: Update for new sparse functionality.
--- a/NEWS	Tue Apr 20 08:42:03 2010 +0200
+++ b/NEWS	Tue Apr 20 09:03:26 2010 +0200
@@ -239,6 +239,26 @@
  ** rem and mod are now built-in functions.  They also handle integer
     types efficiently using integer arithmetic.
 
+ ** Sparse indexing and indexed assignment has been mostly rewritten.
+    Since Octave uses compressed column storage for sparse matrices,
+    major attention is devoted to operations manipulating whole columns.
+    Such operations are now significantly faster, as well as some other
+    important cases.
+
+    Further, it is now possible to pre-allocate a sparse matrix and
+    subsequently fill it by assignments, provided they meet certain
+    conditions.  For more information, consult the `spalloc' function,
+    which is no longer a mere dummy.  Consequently, nzmax and nnz are no
+    longer always equal in Octave. Octave may also produce a matrix with
+    nnz < nzmax as a result of other operations, so you should
+    consistently use nnz unless you really want to use nzmax 
+    (i.e. the space allocated for nonzero elements).
+
+    Sparse concatenation is also affected, and concatenating sparse 
+    matrices, especially larger collections, is now significantly more 
+    efficient. This applies to both the [] operator and the 
+    cat/vertcat/horzcat functions.
+
 Summary of important user-visible changes for version 3.2:
 ---------------------------------------------------------