%   this is a demo for planes, normal vectors etc.
% 
 
 arrow3([0,0,0], [1,0,0],'yellow');
 arrow3([0,0,0], [0,1,0],'yellow');
 arrow3([0,0,0], [0,0,1],'magenta');    % this plots the i,j,k, vectors

             % here we will assume that none of line directions are 0

v = [2, 3, -1];    % along which vector
P = [1,0,2]; 

linepar(P, v, -2,5);   % the last two pars in this function are xmin and xmax

linepar([-1,4,1], [1,1,3],-2,5);       % this is an illustration to 12.5.20