'hold on' command does not work with OCST

[John W. Eaton]

On 19-Feb-2004, 
=?tis-620?Q?=BC=C8.=B4=C3.=C8=D8=C0=AA=D1=C2_=C7=C3=BE=A8=B9=EC=BE=D4?= 
=?tis-620?Q?=C8=D8=B7=B8=D4=EC?= <address@hidden> wrote:

| I try to use command 'hold on' with the following commands in OCST to make
| a comparison graph. But it does not work.
| 
| >> G1 = tf2sys([1],[1 1]);
| >> G2 = tf2sys([1],[1 5]);
| >> hold on
| >> step(G1);
| >> step(G2);
| 
| However if I change to 'bode' command, it can print the graph with two
| traces but the magnitude graph for the second bode command does not show.
| I think that this may be the problem from the calling sequence with OCST
| simulation commands.

It looks like __stepimp__.m calls clearplot before doing any plotting,
even when it will only be plotting for a SISO system.  Maybe it should
only do that if there is more than one input or output.  I propose the
following change.  It looks OK to me, but I'm not sure whether it will
break something else.

jwe


scripts/ChangeLog:

2004-02-18  John W. Eaton  <address@hidden>

        * control/base/__stepimp__.m: Only call clearplot if we will be
        doing multiple plots in the same gnuplot frame.

 
Index: scripts/control/base/__stepimp__.m
===================================================================
RCS file: /usr/local/cvsroot/octave/scripts/control/base/__stepimp__.m,v
retrieving revision 1.7
diff -u -r1.7 __stepimp__.m
--- scripts/control/base/__stepimp__.m  16 Feb 2004 17:45:50 -0000      1.7
+++ scripts/control/base/__stepimp__.m  19 Feb 2004 04:44:21 -0000
@@ -223,7 +223,6 @@
       gset nologscale
       gset autoscale
       gset nokey
-      clearplot();
       if (IMPULSE)
        gm = zeros(NOUT, 1);
        tt = "impulse";
@@ -234,6 +233,9 @@
       endif
       ncols = floor(sqrt(NOUT));
       nrows = ceil(NOUT / ncols);
+      if (ncols > 1 || nrows > 1)
+       clearplot();
+      endif
       for i = 1:NOUT
        subplot(nrows, ncols, i);
        title(sprintf("%s: | %s -> %s", tt,sysgetsignals(sys,"in",inp,1), ...



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