The Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Math Forum » Discussions » Software » comp.soft-sys.matlab

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Spiral with constant velocity (same distance betwee coordinate)
Replies: 7   Last Post: Feb 27, 2013 2:26 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]

Posts: 1,717
Registered: 11/8/10
Re: Spiral with constant velocity (same distance betwee coordinate)
Posted: Feb 26, 2013 7:43 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <kgi99o$jpi$>...
> "Torsten" wrote in message <kghobs$5qf$>...

> > Given a point on the spiral
> > (t0*cos(t0)*Width,t0*sin(t0)*Width),
> > the distance squared to another point on the spiral is given by
> > d^2=(t*cos(t)*Width-t0*cos(t0)*Width)^2 + (t*sin(t)*Width-t0*sin(t0)*Width)^2.
> > This is a quadratic equation in t you can solve analytically.

> IIUC, Torsen's formula is the euclidian 2D distance and not distance along the spiral.
> In order to find the distance along the curve, one need to compute the velocity wrt t, then integrate it, then solve the equation. This might give some mathematical equation not trivial to solved. Burt I haven't wrote i down (it should have a square-root somewhere and I bet it doesn't have a closed integration form).
> Bruno

The OP's passage
> % Calculating the distance between each sample
> dX=diff(x); dY=diff(y); vec=[dX; dY]';
> Distance = sqrt(vec(:,1).^2 + vec(:,2).^2);
> figure(2); plot(Distance)

seems to indicate that he refers to the Euclidean distance between
two subsequent points on the spiral.

Best wishes

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.