Commit 6839e6d5 authored by Paul Ramsey's avatar Paul Ramsey
Browse files

Much better fix for NaN area problem. 


git-svn-id: http://svn.osgeo.org/postgis/trunk@4647 b70326c6-7e19-0410-871a-916f4a2858ee
parent 69f3fb98

liblwgeom/lwgeodetic.c

+1 −8
Original line number Diff line number Diff line
@@ -628,14 +628,7 @@ static double sphere_excess(GEOGRAPHIC_POINT a, GEOGRAPHIC_POINT b, GEOGRAPHIC_P 
	double sign = signum(hcb-hca);

	double ss = (a_dist + b_dist + c_dist) / 2.0;

	double E = tan(ss/2.0)*tan((ss-a_dist)/2.0)*tan((ss-b_dist)/2.0)*tan((ss-c_dist)/2.0);

	/* This is a worrying hack, the number had to be tuned a lot to find 

	   the dividing line between things so small they caused a NaN and 

	   things large enough to effect the final output areas. Probably we

	   will have platform difficulties with this.

	*/

	if( fabs(E) < 1.0e-30 )

		E = 0.0;

	return 4.0 * atan(sqrt(E)) * sign;

	return 4.0 * atan(sqrt(fabs(E))) * sign;

}