[Octave-cvsupdate] SF.net SVN: octave:[9761] trunk/octave-forge/extra/control-devel/inst/@ iddata/diff.m

[<par...@us...>]

Revision: 9761
          http://octave.svn.sourceforge.net/octave/?rev=9761&view=rev
Author:   paramaniac
Date:     2012-03-07 10:14:59 +0000 (Wed, 07 Mar 2012)
Log Message:
-----------
control-devel: touch up diff

Modified Paths:
--------------
    trunk/octave-forge/extra/control-devel/inst/@iddata/diff.m

Modified: trunk/octave-forge/extra/control-devel/inst/@iddata/diff.m
===================================================================
--- trunk/octave-forge/extra/control-devel/inst/@iddata/diff.m	2012-03-07 10:04:59 UTC (rev 9760)
+++ trunk/octave-forge/extra/control-devel/inst/@iddata/diff.m	2012-03-07 10:14:59 UTC (rev 9761)
@@ -16,16 +16,22 @@
 ## along with LTI Syncope.  If not, see <http://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
-## @deftypefn {Function File} {@var{dat} =} cat (@var{dim}, @var{dat1}, @var{dat2}, @dots{})
-## Concatenation of iddata objects along dimension @var{dim}.
+## @deftypefn {Function File} {@var{dat} =} diff (@var{dat})
+## @deftypefnx {Function File} {@var{dat} =} diff (@var{dat}, @var{k})
+## Return @var{k}-th difference of outputs and inputs of dataset @var{dat}.
+## If @var{k} is not specified, default value 1 is taken.
 ## @end deftypefn
 
 ## Author: Lukas Reichlin <luk...@gm...>
 ## Created: March 2012
 ## Version: 0.1
 
-function dat = diff (dat, k)
+function dat = diff (dat, k = 1)
 
+  if (nargin > 2)       # no need to test nargin == 0, this is handled by built-in diff
+    print_usage ();
+  endif
+
   dat.y = cellfun (@(y) diff (y, k), dat.y, "uniformoutput", false);
   dat.u = cellfun (@(u) diff (u, k), dat.u, "uniformoutput", false);
 

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