From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Tue, 13 Oct 2009 19:50:45 +0000 (+0000)
Subject: Much better fix for NaN area problem.
X-Git-Tag: 1.5.0b1~373
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6839e6d5bc050c9624f51e3284def84ae182a5a7;p=postgis

Much better fix for NaN area problem.


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

diff --git a/liblwgeom/lwgeodetic.c b/liblwgeom/lwgeodetic.c
index 48071199e..9ebdbc686 100644
--- a/liblwgeom/lwgeodetic.c
+++ b/liblwgeom/lwgeodetic.c
@@ -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;
 }