Diff of /src/differentiate.cc [000000] .. [db4c4d] Maximize Restore

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+++ b/src/differentiate.cc
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+/*
+Copyright (C) 2002 Ben Sapp
+
+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 Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+*/
+#include <octave/config.h>
+#include <octave/defun-dld.h>
+#include <octave/oct-obj.h>
+#include <ginac/ginac.h>
+#include "ov-vpa.h"
+#include "ov-ex.h"
+#include "symbols.h" 
+
+
+DEFUN_DLD(differentiate,args,,
+"-*- texinfo -*-\n\
+@deftypefn Loadable Function {da_dx =} differentiate(@var{a},@var{x} [, @var{n}])\n\
+\n\
+Return the @var{n}th derivative of @var{a} with respect to @var{x}. If @var{n} is not\n\
+supplied then a default value of 1 is used.\n\
+@end deftypefn")
+{
+  GiNaC::ex expression;
+  GiNaC::ex variable;
+  GiNaC::numeric num;
+  int order;
+  octave_value retval;
+  int nargin = args.length();
+
+  if ((nargin < 2) || (nargin > 3))
+    {
+      print_usage ();
+      return retval;
+    }
+  try 
+    { 
+      if (!get_expression (args(0), expression))
+	{
+	  print_usage ();
+	  return retval;
+	}
+      
+      if (!get_symbol (args(1), variable))
+	{
+	  print_usage ();
+	  return retval;
+	}
+      
+      if (nargin == 3)
+	{
+	  if (!get_numeric (args(2), num))
+	    {
+	      print_usage ();
+	      return retval;
+	    }
+	  order = int(num.to_double ());
+	  if (order < 0)
+	    {
+	      error("must supply an integer greater than zero\n");
+	      return retval;
+	    }
+	}
+      else
+	order = 1;
+
+      retval = octave_value(new octave_ex
+			    (expression.diff
+			     (GiNaC::ex_to<GiNaC::symbol>(variable),order)));
+    }
+  catch (std::exception &e)
+    {
+      error (e.what ());
+      retval = octave_value ();
+    }
+
+  return retval;
+}