by David Legland Geometry library for matlab. Performs geometric computations on points, lines, circles, polygons...
function point = pointOnLine(line, pos)
%POINTONLINE Create a point on a line at a given position on the line
% P = pointOnLine(LINE, POS);
% Creates the point belonging to the line LINE, and located at the
% distance D from the line origin.
% LINE has the form [x0 y0 dx dy].
% LINE and D should have the same number N of rows. The result will have
% N rows ans 2 column (x and y positions).
% See also:
% lines2d, points2d, onLine, onLine, linePosition
% author : David Legland
% INRA - TPV URPOI - BIA IMASTE
% created the 07/04/2004.
angle = lineAngle(line);
point = [line(:,1) + pos .* cos(angle), line(:,2) + pos .* sin(angle)];