isPointOnCircle

ISPOINTONCIRCLE Test if a point is located on a given circle.

   B = isPointOnCircle(POINT, CIRCLE) 
   return true if point is located on the circle, i.e. if the distance to
   the circle center equals the radius up to an epsilon value.

   B = isPointOnCircle(POINT, CIRCLE, TOL) 
   Specifies the tolerance value.

   Example:
   isPointOnCircle([1 0], [0 0 1])
   returns true, whereas
   isPointOnCircle([1 1], [0 0 1])
   return false

   See also:
   circles2d, isPointInCircle

   ---------
   author : David Legland
   INRA - TPV URPOI - BIA IMASTE
   created the 07/04/2004.

0001 function b = isPointOnCircle(point, circle, varargin)
0002 %ISPOINTONCIRCLE Test if a point is located on a given circle.
0003 %
0004 %   B = isPointOnCircle(POINT, CIRCLE)
0005 %   return true if point is located on the circle, i.e. if the distance to
0006 %   the circle center equals the radius up to an epsilon value.
0007 %
0008 %   B = isPointOnCircle(POINT, CIRCLE, TOL)
0009 %   Specifies the tolerance value.
0010 %
0011 %   Example:
0012 %   isPointOnCircle([1 0], [0 0 1])
0013 %   returns true, whereas
0014 %   isPointOnCircle([1 1], [0 0 1])
0015 %   return false
0016 %
0017 %   See also:
0018 %   circles2d, isPointInCircle
0019 %
0020 %   ---------
0021 %   author : David Legland
0022 %   INRA - TPV URPOI - BIA IMASTE
0023 %   created the 07/04/2004.
0024 %
0025 
0026 %   HISTORY
0027 %   22/05/2009 rename to isPointOnCircle, add psb to specify tolerance
0028 
0029 tol = 1e-14;
0030 if ~isempty(varargin)
0031     tol = varargin{1};
0032 end
0033 
0034 d = sqrt(sum(power(point - circle(:,1:2), 2), 2));
0035 b = abs(d-circle(:,3))<tol;
0036