Re: Revised rlocus m-file

[John W. Eaton]

On 25-Feb-2007, Daniel J Sebald wrote:

| What I'm seeing has the makings of a root locus plot, but a bit jumbled 
because of some changes in plotting scripts.  (E.g., seems 1,2,3,etc. are no 
longer options... but I've replaced 1 2 3 with r g b just to see what results.) 
 I'll send you a PNG picture.  Let me know if it is as intended.  Otherwise, 
tell us what you are trying to achieve or what to expect (PNG?) and I might be 
able to suggest some things.  For example, the existing behavior of rlocus() 
looks to try and do some form of shading.  If that is what is intended, gnuplot 
can now create shaded or color polygons.
| 
| Dan
| 
| 
| A. Scottedward Hodel wrote:
| > At the request of my students, I've rewritten the octave rlocus  
| > script.  The revised script implements the following changes:
| > 
| > (1) The dots are now connected: instead of a '.' linespoint style, it  
| > now uses a "-" line style, which makes the plots easier to read.
| > (2) Real axis breakpoints are included in the gains so that the line- 
| > plots are symmetric about the real axis.
| > (3) Bounds on the maximum gain are computed so that asymptotic  behavior 
| > can be seen.
| > 
| > I've done some simple testing on this, but it would be good for a few  
| > others to run it through its paces.
| > 
| > Here's a couple of sample test commands.  The revised rlocus file is  
| > also attached.
| > 
| > I didn't use a diff because it's a pretty substantial rewrite of the  
| > code, other than the portion that smooths the plot.
| > 
| > rlocus(zp([1+j, 1-j], [-1+2*j, -1-2*j,-5, -6, -7],1));
| > rlocus(zp(-0.1,[0 0 -2],1))

I made some changes to the script for the current plotting code and
checked it in.  I think it works better now with the current CVS
Octave and current gnuplot.

Thanks,

jwe