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Subject: Re: Intersection of a plane and finite line segment in 3D space
Date: Mon, 4 Apr 2011 02:21:04 +0000 (UTC)
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I suppose that I missed one thing: P1 = [10 10 10] Do these numbers correspond to x,y and z coordinates of the same point or do they correspond to 'x' coordinates of three points? As far as I understand the second variant is correct. (?)

% Plane
P1 = [10 10 10]; P2 = [20 10 10]; P3 = [10 10 20];
% Line segment
P4 = [5 5 5]; P5 = [13.75 12.5 2.5]; 


"Roger Stafford" wrote in message <inb6ho$d0e$1@fred.mathworks.com>...
> "Liana" wrote in message <inb54p$lpc$1@fred.mathworks.com>...
> > Thanks, Roger. Let me just clarify one more thing: in my case P1 is a point [10 10 10]. so, is it enough just to check if dot(normal,P4-P1) and dot(normal,P5-P1) have opposite sign?
> - - - - - - - - -
>   Yes, it is sufficient.  The respective values of dot(normal,P4-P1) and dot(normal,P5-P1) are unchanged if you replace P1 with P2 or P3, because all three points lie in the plane.
> 
> Roger Stafford