[Octave-cvsupdate] SF.net SVN: octave:[10904] trunk/octave-forge/main/signal

[<car...@us...>]

Revision: 10904
          http://octave.svn.sourceforge.net/octave/?rev=10904&view=rev
Author:   carandraug
Date:     2012-08-24 02:45:33 +0000 (Fri, 24 Aug 2012)
Log Message:
-----------
xcorr2: new option to normalize cross correlation

Modified Paths:
--------------
    trunk/octave-forge/main/signal/NEWS
    trunk/octave-forge/main/signal/inst/xcorr2.m

Modified: trunk/octave-forge/main/signal/NEWS
===================================================================
--- trunk/octave-forge/main/signal/NEWS	2012-08-23 20:09:51 UTC (rev 10903)
+++ trunk/octave-forge/main/signal/NEWS	2012-08-24 02:45:33 UTC (rev 10904)
@@ -16,8 +16,11 @@
  ** The function `rceps' was fixed to work correctly with odd-length inputs.
 
  ** Bugfix in `xcorr2' introduced in 1.1.2 that would not accept "none" as
-    sacle option.
+    scale option.
 
+ ** `xcorr2' accepts a new scale option, "norm", to return the normalized
+    cross correlation.
+
  ** The following functions are new:
     movingrms  schtrig  clustersegment
 

Modified: trunk/octave-forge/main/signal/inst/xcorr2.m
===================================================================
--- trunk/octave-forge/main/signal/inst/xcorr2.m	2012-08-23 20:09:51 UTC (rev 10903)
+++ trunk/octave-forge/main/signal/inst/xcorr2.m	2012-08-24 02:45:33 UTC (rev 10904)
@@ -1,5 +1,6 @@
 ## Copyright (C) 2000 Dave Cogdell <cog...@as...>
 ## Copyright (C) 2000 Paul Kienzle <pki...@us...>
+## Copyright (C) 2012 Carnë Draug <car...@gm...>
 ##
 ## This program is free software; you can redistribute it and/or modify it under
 ## the terms of the GNU General Public License as published by the Free Software
@@ -31,6 +32,9 @@
 ## Scales the raw cross-correlation by the maximum number of elements of @var{a}
 ## and @var{b} involved in the generation of any element of @var{c}.
 ##
+## @item "none"
+## No scaling (this is the default).
+##
 ## @item "unbiased"
 ##
 ## Scales the raw correlation by dividing each element in the cross-correlation
@@ -42,9 +46,9 @@
 ## Normalizes the sequence so that the largest cross-correlation element is
 ## identically 1.0.
 ##
-## @item "none"
+## @item "norm"
 ##
-## No scaling (this is the default).
+## Returns the normalized cross-correlation.
 ## @end itemize
 ## @seealso{conv2, corr2, xcorr}
 ## @end deftypefn
@@ -66,6 +70,8 @@
   ## bias routines by Dave Cogdell (cog...@as...)
   ## optimized by Paul Kienzle (pki...@us...)
   switch lower (biasflag)
+    case {"none"}
+      ## do nothing, it's all done
     case {"biased"}
       c = c / ( min ([ma, mb]) * min ([na, nb]) );
     case {"unbiased"}
@@ -82,10 +88,14 @@
 
     case {"coeff"}
       c = c/max(c(:))';
-    case {"none"}
-      ## do nothing, it's all done
+
+    case {"norm"}
+      a = conv2 (a.^2, ones (size (b)));
+      b = dot (b(:), b(:));
+      c(:,:) = c(:,:) ./ sqrt (a(:,:) * b);
+
     otherwise
-      error ("invalid type of scale %s", biasflag);
+      error ("xcorr2: invalid type of scale %s", biasflag);
   endswitch
 endfunction
 

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