Re: Parametric Function with Lines Instead of Points

Bill,

     It is more that it is counterintuitive to me to be using ((x,y,z) -> t) rather than (t -> (x,y,z)).  However, I guess the same thing appears on the plot.  The reason for reversing the order seems to be to get the correct topology.  So I now have a recipe, but I am not sure I understand what is happening.  Is it written up somewhere what has and doesn't have a topology and what that topology is.  I haven't come across it.

    It is also interesting about the manifold dimension = 1.  It seems to me that the domain, which is the part that goes with the Gridded3DSet, has manifold dimension = 3, and that it is the range that has manifold dimension 1.  (When using your order.)  Or am I just confused.

    I did try to make a cursor consisting of two crossed lines recently.  I noticed that I needed to use a Gridded2DSet, whereas a Linear2D set should have served.  I believe the later gave points, not lines.  I assume this is the same problem.  (I ended up using a shape.)

     Thanks for the information,

    -Ken
 

Bill Hibbard wrote:
Ken,

This works because the lines between points must come from
a topology, and the Gridded3DSet defines a topology (a sequence
of lines in the case of manifold dimension = 1). Given a FlatField
with MathType (t -> (x, y, z)), the display logic should not assume
a topology among the (x, y, z) range points since there are plenty
of examples where there would not be any.

By the way, it looks like your messages are making it to the list
now so no more need to CC Tom and me. I should have told
you that I use hiding@xxxxxxxxx for all mailing list traffic (I'm
hiding from spammers harvesting addresses). I suspect the list
server rejected your first message because the embedded image
exceeded the message length limit.

Cheers,
Bill

----- Original Message -----
From: "Kenneth Evans"
To: Visad
Subject: Re: Parametric Function with Lines Instead of Points
Date: Tue, 27 Mar 2007 14:27:04 -0500

Bill,

     Thanks.  That was easy and worked.  I need to think about why, though.

     In regard to the email's not getting through:  Is it possibly because I had a screen dump in the body, rather than as an attachment.  (I do that all the time and didn't think.)

     Thanks again,

    -Ken

Bill Hibbard wrote:
Hi Ken,

I want to plot a function (t -> (x, y, z)), for example, an orbit.  I can do
this OK, but I get points on the plot and I would like lines.  Can I do this
and if so, how?  It doesn't seem like it should be hard, but I haven't
figured it out.

You can do this by using your data to construct a
FlatField with MathType (((x, y, z) -> t) and whose
domain Set is a Gridded3DSet with manifold dimension
 = 1. You should be able to find the Gridded3DSet
constructor for manifold dimension = 1.

If you have any follow up questions please send them
to the VisAD mailing list, as you tried to do before,
and hopefully they'll get through. You can CC Tom and
me just to make sure.

Good luck,
Bill
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