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From: "Ben " <gogo.xa@gmail.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: intersection of two surfaces
Date: Wed, 17 Nov 2010 04:48:04 +0000 (UTC)
Organization: Johns Hopkins University
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Thanks very much Roger,  it's solved with your kind help!

Ben

"Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <ibvls3$q33$1@fred.mathworks.com>...
> "Ben " <gogo.xa@gmail.com> wrote in message <ibvl1s$3tf$1@fred.mathworks.com>...
> > .......
> > What if the plane is represented using a normal and a point on it?  Thank you.
> > .......
> - - - - - - - - -
>   If P0 is the point on the plane and N a normal to the plane.  Then the equation of the plane is dot(P-P0,N) = 0.  Or expressed in separate coordinates:
> 
>  nx*x + ny*y + nz*z - (nx*x0+ny*y0+nz*z0) = 0.
> 
> where P0 = [x0,y0,z0] and N = [nx,ny,nz].
> 
>   To use this to find your "middle" plane you need to use an N which is normalized.  Do this:
> 
>  N = N/norm(N);
> 
> Roger Stafford