From 303ee78bdd9b32da7d972d8e7202207e145f94e4 Mon Sep 17 00:00:00 2001
From: Davis King <davis@dlib.net>
Date: Wed, 28 Jul 2010 23:50:20 +0000
Subject: [PATCH] Minor change to get better cache locality.  Gives a nice
 speedup though.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403797
---
 dlib/svm/krr_trainer.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/dlib/svm/krr_trainer.h b/dlib/svm/krr_trainer.h
index 0f8ee19ca..b53fe5aff 100644
--- a/dlib/svm/krr_trainer.h
+++ b/dlib/svm/krr_trainer.h
@@ -372,9 +372,12 @@ namespace dlib
             matrix<column_matrix_type,0,1,mem_manager_type > Vx;
             if (lambda == 0 || output_looe)
             {
+                // Save the transpose of V into a temporary because the subsequent matrix
+                // vector multiplies will be faster (because of better cache locality).
+                const general_matrix_type transV(trans(V));
                 Vx.set_size(proj_x.size());
                 for (long i = 0; i < proj_x.size(); ++i)
-                    Vx(i) = squared(trans(V)*proj_x(i));
+                    Vx(i) = squared(transV*proj_x(i));
             }
 
             the_lambda = lambda;