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+++ b/scripts/control/syschnames.m
@@ -0,0 +1,141 @@
+# Copyright (C) 1996 A. Scottedward Hodel 
+#
+# This file is part of Octave. 
+#
+# Octave 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, or (at your option) any 
+# later version. 
+# 
+# Octave 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 Octave; see the file COPYING.  If not, write to the Free 
+# Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
+ 
+function retsys = syschnames(sys,opt,list,names)
+# retsys = syschnames(sys,opt,list,names)
+# change the names of selected inputs, outputs and states.
+# inputs:
+# 	sys: system data structure
+#	opt: []: change default name (output)
+#	     "out": change selected output names
+#	     "in": change selected input names
+#	     "st": change selected state names	 
+#	     "yd": change selected outputs from discrete to continuous or 
+#		   from continuous to discrete.
+#
+#     	list: vector of indices of outputs, yd, inputs, or
+#             states whose respective names should be changed
+#
+#    	names: strings or string arrays containing
+#              names corresponding to the lists above.  To
+# 	       change yd, use a vector.  Set the name to 0 for continuous, 
+#	       or 1 for discrete.
+# outputs:
+#    retsys=sys with appropriate signal names changed 
+#            (or yd values, where appropriate)
+
+# Written by John Ingram August 1996
+# $Revision: 1.3 $
+# $Log: syschnames.m,v $
+# Revision 1.3  1998/07/17 15:31:06  hodelas
+# use is_empty instead of max(size(...))
+#
+
+  save_val = implicit_str_to_num_ok;	# save for later
+  implicit_str_to_num_ok = 1;
+
+  if (nargin != 4)
+    usage("retsys=syschnames(sys,opt,list[,names])");
+  elseif (!is_struct(sys))
+    error("sys must be a system data structure");
+  elseif (isempty(opt))
+    opt = "out";
+  elseif( ! isstr(opt) )
+    error("opt must be a string");
+  elseif( ! (strcmp(opt,"out") + strcmp(opt,"yd") + ...
+    strcmp(opt,"in") + strcmp(opt,"st") ) )
+    error("opt must be one of [], ""out"", ""yd"", ""in"", or ""st""");
+  elseif(min(size(list)) > 1)
+    disp("syschnames: list=")
+    disp(list);
+    error("list must be a vector")
+  endif
+
+  if (strcmp(opt,"out"))
+    # update output names
+    sys.outname = syschnamesl(list,sys.outname,names,"outlist");
+  elseif (strcmp(opt,"in"))
+    sys.inname = syschnamesl(list,sys.inname,names, "inlist");
+  elseif (strcmp(opt,"st"))
+    sys.stname = syschnamesl(list,sys.stname,names,"stlist");
+  else
+    # it's yd
+    ym = max(size(list));
+    ys = min(size(list));
+    maxn = rows(sys.outname);
+
+    if(ym != 0)
+      if( (ym  > maxn) | (ys != 1) )
+        error(["system has ",num2str(maxn)," outputs, ", ...
+	  "list=(",num2str(rows(list)),"x",num2str(columns(list)),")"]);
+      endif
+
+      if( ym != length(names))
+        error(["list has ",num2str(ym)," entries, and names has ",...
+		num2str(length(names))," entries."]);
+      endif
+
+      if (min((names == 1) | (names == 0)) == 0)
+        error("yd must be either zero or one");
+      endif
+
+      if (max(list) > maxn)
+        error(["The largest entry in the list is ",num2str(max(list)),...
+		" exceeds number of outputs=",num2str(maxn)])
+      endif      
+
+      if (max(names) && (sys.tsam == 0) )
+        warning("syschnames: discrete outputs with tsam=0; setting tsam=1");
+        disp("	effected outputs are:")
+        if(is_siso(sys))
+          outlist(sys.outname,"	",[],list);
+        else
+          outlist(sys.outname(list,:),"	",[],list);
+        endif
+        sys.tsam = 1;
+      endif
+
+      # reshape everything as a column vector
+      sys.yd = reshape(sys.yd,length(sys.yd),1);
+      names  = reshape(names,length(names),1);
+
+	#disp("syschnames: list=")
+	#disp(list)
+	#disp("syschnames: names=")
+	#disp(names)
+	#disp("syschnames: sys.yd=")
+	#disp(sys.yd)
+
+      sys.yd(list) = names;
+    
+      if ((min(sys.yd) == 0) && (max(sys.yd) == 0) && (sys.tsam > 0) )
+        warning("discrete states but no discrete outputs selected");
+      endif
+
+    endif
+    
+  endif
+
+  retsys = sys;
+  implicit_str_to_num_ok = save_val;	# restore value
+
+  #disp("syschnames: exiting with")
+  #retsys
+  #disp("/syschnames")
+
+endfunction