# HG changeset patch
# User jwe
# Date 1051818130 0
# Node ID c05051baf03be369323e02619959ccd92d944669
# Parent  f52b3f1a93995889e6ff32a45a671e348e5bbb5c
[project @ 2003-05-01 19:41:57 by jwe]

diff --git a/scripts/ChangeLog b/scripts/ChangeLog
--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,3 +1,8 @@
+2003-05-01  John W. Eaton  <jwe@bevo.che.wisc.edu>
+
+	* control/system/sysadd.m: If systems are not "tf", convert before
+	adding.
+
 2003-05-01  Paul Kienzle <pkienzle@users.sf.net>
 
 	* image/imagesc.m: Accept data limits parameter for colormap.
diff --git a/scripts/control/system/sysadd.m b/scripts/control/system/sysadd.m
--- a/scripts/control/system/sysadd.m
+++ b/scripts/control/system/sysadd.m
@@ -73,19 +73,25 @@
   endfor
 
   ## perform the add
-  if(nargin == 2)
-    Gsys = nth(arglist,1);   Hsys = nth(arglist,2);
-    if( strcmp(sysgettype(Gsys),"tf") | strcmp(sysgettype(Hsys),"tf") )
-      ## see if adding  transfer functions with identical denominators
+  if (nargin == 2)
+    Gsys = nth(arglist,1);
+    Hsys = nth(arglist,2);
+
+    if (! strcmp (sysgettype (Gsys), "tf"))
       [Gnum,Gden,GT,Gin,Gout] = sys2tf(Gsys);
+    endif
+
+    if (! strcmp (sysgettype (Hsys),"tf"))
       [Hnum,Hden,HT,Hin,Hout] = sys2tf(Hsys);
-      if(length(Hden) == length(Gden) )
-        if( (Hden == Gden) & (HT == GT) )
-          sys = tf2sys(Gnum+Hnum,Gden,GT,Gin,Gout);
-          return
-        endif
-        ## if not, we go on and do the usual thing...
+    endif
+
+    ## see if adding  transfer functions with identical denominators
+    if (length(Hden) == length(Gden) )
+      if( (Hden == Gden) & (HT == GT) )
+        sys = tf2sys(Gnum+Hnum,Gden,GT,Gin,Gout);
+        return
       endif
+      ## if not, we go on and do the usual thing...
     endif
 
     ## make sure in ss form