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Catch a possible floating point error in SGGeodesy::SGCartToGeod() for cartesian coordinates close to the geocenter region.

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torsten
2009-09-22 14:17:45 +00:00
committed by Tim Moore
parent 3456434e37
commit bcf727cf58
1 changed files with 11 additions and 0 deletions
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11
simgear/math/SGGeodesy.cxx
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@@ -79,6 +79,17 @@ SGGeodesy::SGCartToGeod(const SGVec3<double>& cart, SGGeod& geod)
double Y = cart(1);
double Z = cart(2);
double XXpYY = X*X+Y*Y;
if( XXpYY + Z*Z < 25 ) {
// This function fails near the geocenter region, so catch that special case here.
// Define the innermost sphere of small radius as earth center and return the
// coordinates 0/0/-EQURAD. It may be any other place on geoide's surface,
// the Northpole, Hawaii or Wentorf. This one was easy to code ;-)
geod.setLongitudeRad( 0.0 );
geod.setLongitudeRad( 0.0 );
geod.setElevationM( -EQURAD );
return;
}
double sqrtXXpYY = sqrt(XXpYY);
double p = XXpYY*ra2;
double q = Z*Z*(1-e2)*ra2;