y=leftof(p,a,b)

function y=leftof(p,a,b)
%function y=leftof(p,a,b)
%Return 1 if the point p is to the left of the line ab.
%For a n x 2 list of points p, return a vector of results.
%
% Author: Richard Schreier, Oregon State University. <[e-mail]>

%Translate to the origin and do the check
p = p - a(ones(1,size(p,1)),:);
b = b-a;
y= b(1)*p(:,2) > b(2)*p(:,1);