findLine

 Find first order (line) approx. for points p1, p2, p3

0001 
0002 function [pl, vec] = findLine(p1, p2, p3)
0003 % Find first order (line) approx. for points p1, p2, p3
0004 x = [p1(1) p2(1) p3(1)]';
0005 y = [p1(2) p2(2) p3(2)]';
0006 
0007 if (sum(x)/3) == x(1)
0008     pl = [x(1) 1];
0009     vec = [0 1];
0010 else
0011 p = polyfit(x,y,1);
0012 u = [min(x):0.01:max(x)]';
0013 v = p(1)*u +p(2);
0014 vec = [u(length(u))-u(1) v(length(v))-v(1)];  
0015 pl = [u(1) v(1)];
0016 end
0017 pl;
0018 vec;