[Qgis-developer] (prabable) bug in ellipsoid semi-minor axis calculation inside QgsDistanceArea

[G. Allegri]

In Qgis the semi-minor axis of the ellipsoid is calculated [1] with:

b = a - (f/a)

where
b = semi-minor axis
a = semi-majot axis
f = inverse flattening

while it should be:

b = a - (a/f)

In Qgis the WGS84 semi-minor axis is 6378136,xxx
while it should be 6356752.xxx

This causes wrong distance calculations on ellipsoid as reported here:
http://lists.osgeo.org/pipermail/qgis-user/2012-April/016535.html

giovanni

[1]
http://trac.osgeo.org/qgis/browser/trunk/qgis/src/core/qgsdistancearea.cpp#L153
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