Re: Drawing shapes / non-function plots in Octave?

[Quentin Spencer]

edA-qa mort-ora-y wrote:

> Is it possible to draw shapes using the plot functions in octave?  In 
> particular I want to visualize the vector work that I am doing, but it 
> doesn't conform to a simple x=y mapping.
>
> I am aware that I can do this:
>     hold on;
>     gplot( [ P1; P2 ] );
>     gplot( [ P3; P4 ] );
> to draw lines between arbitrary points.  But this starts going 
> extremely slow after about 50 lines or so.
>
> Is there a better way to do this?
>
> I added an example at http://wiki.octave.org/wiki.pl?SimpleExamples of 
> on of my problems I want to visualize -- using the above notation.

I looked at your example on the wiki, but it didn't work for me because 
of a undefined function call to "unit", which I suspect is your own code 
that you forgot to include. If you want to plot lines between multiple 
arbitrary points with one plot command, it's easier to just do
plot([x1a,x2a; x1b,x2b; x1c,x2c; ...],[y1a,y2a; y1b,y2b; y1c,y2c; ...])

This draws lines from (x1a,y1a) to (x2a,y2a) etc. They will all be the 
same color if you include a line style argument. A quick demonstration 
involving a lot of lines is:
plot(rand(2,100),rand(2,100),'1');

I'm not sure what you mean by drawing shapes. I don't know how do to 
filled shapes, but if outlines are adequate, it seems like this method 
should be straightforward.

Quentin



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