straight line and plane intersection

%plane_line_intersect computes the intersection of a plane and a segment (or a straight line)
% Inputs:
% n: normal vector of the Plane
% V0: any point that belongs to the Plane
% P0: end point 1 of the segment P0P1
% P1: end point 2 of the segment P0P1
%
%Outputs:
% I is the point of interection
% Check is an indicator:
% 0 => disjoint (no intersection)
% 1 => the plane intersects P0P1 in the unique point I
% 2 => the segment lies in the plane
% 3=>the intersection lies outside the segment P0P1
%
% Example:
% Determine the intersection of following the plane x+y+z+3=0 with the segment P0P1:
% The plane is represented by the normal vector n=[1 1 1]
% and an arbitrary point that lies on the plane, ex: V0=[1 1 -5]
% The segment is represented by the following two points
% P0=[-5 1 -1]
%P1=[1 2 3]
% [I,check]=plane_line_intersect([1 1 1],[1 1 -5],[-5 1 -1],[1 2 3]);