title: How to do linear interpolation?
body: <p>I have line segment with start s(x1,y1) and end e(x2,y2). I have calculated distance between s and e by using euclidean distance 
      d = sqrt((x1-x2)<em>(x1-x2) + (y1-y2)</em>(y1-y2))
  How to find out point on the line segment at distance d1 (0 &lt; d1&lt; d)? </p>