Intersection point(s) of a line and a circle.

   INTERS = intersectLineCircle(LINE, CIRCLE);
   Returns a 2-by-2-by-N array, containing on each row the coordinates of
   an intersection point for each line-circle pair, i.e. INTERS(:,:,k)
   contains the intersections between LINE(k,:) and CIRCLE(k,:).

   If a line-circle pair does not intersect, the corresponding results are
   set to NaN. 

   Example
     % base point
     center = [10 0];
     % create vertical line
     l1 = [center 0 1];
     % circle
     c1 = [center 5];
     pts = intersectLineCircle(l1, c1)
     pts =
     10   -5
     10    5
     % draw the result
     figure; clf; hold on;
     axis([0 20 -10 10]);
     drawLine(l1);
     drawCircle(c1);
     drawPoint(pts, 'rx');
     axis equal;

   See also
   lines2d, circles2d, intersectLines, intersectCircles

   References
   http://local.wasp.uwa.edu.au/~pbourke/geometry/sphereline/
   http://mathworld.wolfram.com/Circle-LineIntersection.html

Package: matgeom