function [n,Po,u,v,lu,lv,c,Puv] = polygoninrectangle(P) returns normal unit vector n, point Po, lateral unit vector u, lateral unit vector v, lateral length lu, lateral length lv, centre c and 2-column matrix Puv, i.e. a description of the rectangle comprising the polygon defined by three-dimensional points in 3-column matrix P. The points in P must be in counter-clockwise ordre. Whether this might be true, is not checked. The counter-clockwise ordre is seen, when one sees the "upper" or "front" surface of the polygon, i.e. the direction of sight is oposite to the normal of the plane of the polygon. The lateral of the rectangle in u direction is parallel to the line from the first to the second point listed in P. Point Po is the three-dimensional point where u=0 and v=0. Matrix Puv lists the u and v coordinates of the points listed in P. Whether each point in P is really within the plane through the first two points and the last point listed in P, is not checked! (c) 2026 fabien van mook 2026.08.20 release of this file within package "fvm-geometry" under GNU GPLv3+