virtual double MgCoordinateSystem::MeasureGreatCircleDistance	(	double	x1,
		double	y1,
		double	x2,
		double	y2
	)		[pure virtual]

Measures the distance between two coordinates (x1, y1) and (x2, y2) in coordinate system units.

Parameters:

x1	The first X coordinate
y1	The first Y coordinate
x2	The second X coordinate
y2	The second Y coordinate

Returns:

The great circle distance from (x1, y1) to (x2, y2) in coordinate system units