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https://issues.apache.org/jira/browse/GEOMETRY-71?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17010038#comment-17010038
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Baljit Singh commented on GEOMETRY-71:
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I added tests for area and boundary size. The area size is correct for both
counterclockwise and clockwise. However, the boundary size test is failing for
both windings. The error in the boundary size seems small (0.004%), but I
wonder if that gets accumulated with float-point error.
Btw, there is a
[FMA|https://docs.oracle.com/javase/9/docs/api/java/lang/Math.html#fma-double-double-double-]
as of Java 9. On modern hardware, its fast (HotSpot intrinsic). On older
hardware, it relies on the slower BigDecimal.
> Investigate Spherical Barycenter Accuracy
> -----------------------------------------
>
> Key: GEOMETRY-71
> URL: https://issues.apache.org/jira/browse/GEOMETRY-71
> Project: Apache Commons Geometry
> Issue Type: Bug
> Reporter: Matt Juntunen
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> The current code for computing spherical barycenters in
> {{ConvexArea2S.getBarycenter()}} seems to suffer from floating point accuracy
> issues. The {{ConvexArea2STest.checkBarycenterConsistency()}} method checks
> the consistency of the barycenter computation of a region by splitting the
> region into two sections, computing the area and barycenter of each section,
> and then computing the combined barycenter of the sections by adding the
> barycenter of each scaled by its corresponding area. It is expected that the
> combined barycenter computed in this way should equal the barycenter computed
> for the region as a whole. However, in practice, a large epsilon value is
> needed in the comparison in order for the tests to pass. We need to
> investigate why this is the case.
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