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  1. Commons Math
  2. MATH-846

Rotation constructor does wrong calculation

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Details

    • Bug
    • Status: Closed
    • Major
    • Resolution: Duplicate
    • 3.0
    • 3.1
    • None
    • Windows java 1.7r5

    Description

      The following code produces the wrong result. The resulting Rotation is does not even hold a normalized quaternion:

      final Vector3D u1 = new Vector3D(1.0, 0.0, 0.0);
      final Vector3D u2 = new Vector3D(1.0, -1.0, 0.0);
      final Vector3D v1 = new Vector3D(0.9999999, 0., 0.0);
      final Vector3D v2 = new Vector3D(0., 1., 0.0);
      final Rotation rot = new Rotation(u1, u2, v1, v2);
      System.err.println("rot quaternion: " + rot.getQ0() + " " + rot.getQ1() + " " + rot.getQ2() + " " + rot.getQ3());

      For me it outputs:

      rot quaternion: 0.0 0.0 0.0 -7.450580596923828E-9

      The correct output should have been:

      rot quaternion: 0.0 1.0 0.0 0.0

      The constructor seems to be hitting some kind of numerical instability.

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            Unassigned Unassigned
            fhess Frank Hess
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              Created:
              Updated:
              Resolved: