[jira] [Commented] (GEOMETRY-86) Point2S.antipodal() or Point2S.from() is incorrect.

["Baljit Singh (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/GEOMETRY-86?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17010299#comment-17010299 ] 

Baljit Singh commented on GEOMETRY-86:
--------------------------------------

Likely it is the antipodal, which should be:


{code:java}
    public Point2S antipodal() {
        return new Point2S(PlaneAngleRadians.PI + azimuth, PlaneAngleRadians.PI - polar, vector.negate());
    }
{code}


> Point2S.antipodal() or Point2S.from() is incorrect.
> ---------------------------------------------------
>
>                 Key: GEOMETRY-86
>                 URL: https://issues.apache.org/jira/browse/GEOMETRY-86
>             Project: Apache Commons Geometry
>          Issue Type: Bug
>            Reporter: Baljit Singh
>            Priority: Major
>
> {code:java}
>     @Test
>     public void testAntipodal() {
>         Point2S point = Point2S.of(1.0, 1.0);
>         Point2S antipodal = point.antipodal();
>         Point2S fromNeg = Point2S.from(point.getVector().negate());
>         System.out.println(String.format("Point2S: %s, Vector: %s", point, point.getVector()));
>         System.out.println(String.format("Point2S: %s, Vector: %s", antipodal, antipodal.getVector()));
>         System.out.println(String.format("Point2S: %s, Vector: %s", fromNeg, fromNeg.getVector()));
>     }
> {code}
> This prints:
> Point2S: (1.0, 1.0), Vector: (0.4546487134128409, 0.7080734182735712, 0.5403023058681398)
> Point2S: (*5.283185307179586*, 2.141592653589793), Vector: (-0.4546487134128409, -0.7080734182735712, -0.5403023058681398)
> Point2S: (*4.141592653589792*, 2.141592653589793), Vector: (-0.4546487134128409, -0.7080734182735712, -0.5403023058681398)
> SphericalTestUtils.assertPointsEq does not detect the error because the point.getVector() and copy.getVector() are equal, and therefore the distance between these points is equal.



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