Baljit Singh created MATH-1507:
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Summary: Barycenter of a clockwise SphericalPolygonsSet is
incorrect.
Key: MATH-1507
URL: https://issues.apache.org/jira/browse/MATH-1507
Project: Commons Math
Issue Type: Bug
Affects Versions: 3.6.1
Reporter: Baljit Singh
Let's say there is a circle on a spherical surface.
* The circle center is given by S2Point(theta=-0.6981, phi=0.87266). The
radius is irrelevant.
* Let's discretize this circle into a polygon with 100 edges. Let's make the
orientation {color:#FF0000}clockwise{color}.
* Since its a clockwise circle, from symmetry, we know that the barycenter
would be around S2Point(theta=2.44346, phi=2.268928), which is just the reverse
of the normal vector at the circle center.
* Using SphericalPolygonsSet, the calculated barycenter is
S2Point(theta=2.4922, phi=0.69889).
A few things I've already tested:
* For counterclockwise, the result is correct.
* The perimeter and surface area of the polygon is correct for both
counterclockwise and clockwise.
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