# plotting normal vector in 3d

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Jack_111 on 30 Jul 2013
I have three points P0=[x0,y0,z0], P1=[x1,y1,z1] P2=[x2,y2,z2] and I want to calculate the normal out of them what I did is
normal = cross(P0-P1, P0-P2);
and then I wanted to plot the normal so what I did is,
c = normal + P0 %end position of normal vector
quiver3(P0(1), P0(2), P0(3), c(1), c(2), c(3)); but it didn't work any suggestions please
%......Edited

Matt Kindig on 30 Jul 2013
doc quiver3

Jack_111 on 31 Jul 2013
The answer is larger than -8.278e-25
Matt Kindig on 31 Jul 2013
Then what I said above is correct. Your dot product is as close to zero as you'll be able to calculate. In other words, your calculated vector (from the cross product) is as close to normal to the plane as you'll be able to get.
I'm not really sure what else to say. Your code is correct, your answer is correct, and that's that. Read http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html for why exact floating-point calculations are not possible with a computer.
Jack_111 on 1 Aug 2013