MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi
Learn moreOpportunities for recent engineering grads.
Apply TodayMATLAB Central > MATLAB Newsreader > Vectors on ellipsoid surface 

I plotted an ellipsoid [x,y,z]=ellipsoid (standard in Matlab) 
Subject: Vectors on ellipsoid surface From: Torsten Hennig Date: 21 May, 2010 10:49:40 Message: 2 of 30 
> I plotted an ellipsoid [x,y,z]=ellipsoid (standard 
I had to be more clear indeed, the point C lies within the ellipsoid, so not on the surface. 
Where the normal vector is perpendicular to the Line from P1 to P2 and runs through C and C'. 
Subject: Vectors on ellipsoid surface From: Torsten Hennig Date: 21 May, 2010 12:21:06 Message: 5 of 30 
> I had to be more clear indeed, the point C lies 
You are correct. The one with the shortest distance to the surface is the one I am interested in. But if that is too much trouble, I can calculate that myself. If I just had the two points, that would make my day. 
Subject: Vectors on ellipsoid surface From: Torsten Hennig Date: 21 May, 2010 12:55:26 Message: 7 of 30 
> Where the normal vector is perpendicular to the Line 
Dear Torsten, 
Subject: Vectors on ellipsoid surface From: Torsten Hennig Date: 21 May, 2010 15:34:49 Message: 9 of 30 
> Dear Torsten, 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 21 May, 2010 17:28:05 Message: 10 of 30 
This problem of projection on ellipse in 2D can be solved without optimization toolbox, here is the demo: 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 21 May, 2010 17:35:21 Message: 11 of 30 
Sorry make, it: 
Thanks Bruno for all the effort. Though, my ellipsoid is a 3D figure. How difficult is it to adjust your code for 3D? 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 21 May, 2010 22:21:05 Message: 13 of 30 
"Els " <y.e.t.reeuwijk@student.utwente.nl> wrote in message <ht6ob1$20d$1@fred.mathworks.com>... 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 22 May, 2010 07:24:23 Message: 14 of 30 
Here is the implementation of the idea I put earlier: 
Subject: Vectors on ellipsoid surface From: Roger Stafford Date: 23 May, 2010 03:50:04 Message: 15 of 30 
"Els " <y.e.t.reeuwijk@student.utwente.nl> wrote in message <ht5ldf$7tf$1@fred.mathworks.com>... 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 23 May, 2010 06:33:05 Message: 16 of 30 
"Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <hta8lc$e4f$1@fred.mathworks.com>... 
Subject: Vectors on ellipsoid surface From: Roger Stafford Date: 23 May, 2010 06:37:03 Message: 17 of 30 
"Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <hta8lc$e4f$1@fred.mathworks.com>... 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 23 May, 2010 09:01:08 Message: 18 of 30 
I have extended Roger's idea of parametrization with respect to Lagrange parameter (he call it "t", I call it "lambda") to ndimensional ellipsoid. The polynomial to be solved is 2*n in order. 
"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <htaqsk$5h1$1@fred.mathworks.com>... 
Subject: Vectors on ellipsoid surface From: Mark Shore Date: 23 May, 2010 13:51:04 Message: 20 of 30 
I have to say results can be very impressive when a challenging problem catches the interest of CSSM contributors. 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 23 May, 2010 14:38:03 Message: 21 of 30 
"Els " <y.e.t.reeuwijk@student.utwente.nl> wrote in message <htba3v$iq3$1@fred.mathworks.com>... 
> > But what I am not getting is how to give in P1 and P2 (the two points between which C lies), and is the projected C in 90 degrees of this line? 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 24 May, 2010 07:08:03 Message: 23 of 30 
"Els " <y.e.t.reeuwijk@student.utwente.nl> wrote in message <htbpdd$e9i$1@fred.mathworks.com>... 
Ok, you are correct. The orthogonal axis problem I solved now. 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 24 May, 2010 09:28:05 Message: 25 of 30 
"Els " <y.e.t.reeuwijk@student.utwente.nl> wrote in message <htdetc$c98$1@fred.mathworks.com>... 
Dear Bruno, 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 24 May, 2010 15:08:10 Message: 27 of 30 
You want C' on (E) and CC' orthogonal to P1P2, right? Let us denote by (P) the plane passing through C and perpendicular to vector P1P2. This plane must contain C' (because you want CC' to be orthogonal to P1P2) and C as well. 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 24 May, 2010 15:51:19 Message: 28 of 30 
I clean up the code and better structure it. The convolution part is now carried out in an optimal manner (not at all important for 2D or 3D, but it's much nicer that way). The submission on FEX is here: 
Dear Bruno, 
Subject: Vectors on ellipsoid surface From: Bruno Luong Date: 24 May, 2010 18:09:05 Message: 30 of 30 
Here are few mistakes I catch: 
A tag is like a keyword or category label associated with each thread. Tags make it easier for you to find threads of interest.
Anyone can tag a thread. Tags are public and visible to everyone.