[Octave-cvsupdate] SF.net SVN: octave:[10369] trunk/octave-forge/main/control/inst

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

Revision: 10369
          http://octave.svn.sourceforge.net/octave/?rev=10369&view=rev
Author:   paramaniac
Date:     2012-05-06 20:17:43 +0000 (Sun, 06 May 2012)
Log Message:
-----------
control: fix display of transfer function variable z^-1

Modified Paths:
--------------
    trunk/octave-forge/main/control/inst/filt.m
    trunk/octave-forge/main/control/inst/tfpoly2str.m

Modified: trunk/octave-forge/main/control/inst/filt.m
===================================================================
--- trunk/octave-forge/main/control/inst/filt.m	2012-05-06 19:36:54 UTC (rev 10368)
+++ trunk/octave-forge/main/control/inst/filt.m	2012-05-06 20:17:43 UTC (rev 10369)
@@ -57,9 +57,9 @@
 ## 
 ## Transfer function 'H' from input 'u1' to output ...
 ## 
-##            3 z     
-##  y1:  -------------
-##       z^2 + 4 z + 2
+##             3 z^-1       
+##  y1:  -------------------
+##       1 + 4 z^-1 + 2 z^-2
 ## 
 ## Sampling time: unspecified
 ## Discrete-time model.

Modified: trunk/octave-forge/main/control/inst/tfpoly2str.m
===================================================================
--- trunk/octave-forge/main/control/inst/tfpoly2str.m	2012-05-06 19:36:54 UTC (rev 10368)
+++ trunk/octave-forge/main/control/inst/tfpoly2str.m	2012-05-06 20:17:43 UTC (rev 10369)
@@ -27,13 +27,21 @@
 
 function str = tfpoly2str (p, tfvar = "x")
 
+  ## TODO: simplify this ugly code
+
   str = "";
 
   lp = numel (p);
 
-  if (lp > 0)
-    ## first element (lowest order 0)
-    a = p(1);
+  if (lp > 0)               # first element (lowest order)
+    idx = find (p);         # first non-zero element
+    if (isempty (idx))
+      str = "0";
+      return;
+    else
+      idx = idx(1);
+    endif
+    a = p(idx);
 
     if (a < 0)
       cs = "-";
@@ -41,11 +49,18 @@
       cs = "";
     endif
     
-    str = [cs, num2str(abs (a), 4)];
+    if (idx == 1)
+      str = [cs, num2str(abs (a), 4)];
+    else
+      if (abs (a) == 1)
+        str = [cs, __variable__(tfvar, idx-1)];
+      else
+        str = [cs, __coefficient__(a), " ", __variable__(tfvar, idx-1)];
+      endif
+    endif
 
-    if (lp > 1)
-      ## remaining elements of higher order
-      for k = 2 : lp
+    if (lp > idx)           # remaining elements of higher order
+      for k = idx+1 : lp
         a = p(k);
 
         if (a != 0)
@@ -84,6 +99,6 @@
 
 function str = __variable__ (tfvar, n)
 
-    str = [tfvar, "^-", num2str(n)];
+  str = [tfvar, "^-", num2str(n)];
 
 endfunction

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