/** Path & edge are the same, directions are reverse, neg. to pos. */
  @Test
  public void testPathStateConvert7() {

    final Path startPath =
        TestUtils.makeTmpPath(
            graph,
            true,
            new Coordinate(20, -10),
            new Coordinate(10, -10),
            new Coordinate(10, 0),
            new Coordinate(0, 0));
    final Matrix covar =
        MatrixFactory.getDefault()
            .copyArray(new double[][] {new double[] {126.56, 8.44}, new double[] {8.44, 0.56}});
    final MultivariateGaussian startBelief =
        new AdjMultivariateGaussian(VectorFactory.getDefault().createVector2D(-2.5d, 1d), covar);
    final PathStateDistribution currentBelief = new PathStateDistribution(startPath, startBelief);

    final Path newPath =
        TestUtils.makeTmpPath(graph, false, new Coordinate(10, 0), new Coordinate(0, 0));

    final PathStateDistribution result = currentBelief.convertToPath(newPath);

    AssertJUnit.assertEquals("distance", 7.5d, result.getMean().getElement(0), 0d);
    AssertJUnit.assertEquals("velocity", 1d, result.getMean().getElement(1), 0d);
  }
  @Test
  public void testPathStateConvert2() {
    final Path startPath =
        TestUtils.makeTmpPath(graph, false, new Coordinate(0, 0), new Coordinate(10, 0));

    final Matrix covar =
        MatrixFactory.getDefault()
            .copyArray(new double[][] {new double[] {126.56, 8.44}, new double[] {8.44, 0.56}});
    final MultivariateGaussian startBelief =
        new AdjMultivariateGaussian(VectorFactory.getDenseDefault().createVector2D(0d, 1d), covar);
    final PathStateDistribution currentBelief = new PathStateDistribution(startPath, startBelief);

    final Vector groundLoc =
        MotionStateEstimatorPredictor.getOg()
            .times(currentBelief.getGroundDistribution().getMean());
    AssertJUnit.assertEquals("initial state x", 0d, groundLoc.getElement(0), 0d);
    AssertJUnit.assertEquals("initial state y", 0d, groundLoc.getElement(1), 0d);

    final Path newPath =
        TestUtils.makeTmpPath(
            graph,
            true,
            new Coordinate(20, -10),
            new Coordinate(10, -10),
            new Coordinate(10, 0),
            new Coordinate(0, 0));

    final PathStateDistribution result = currentBelief.convertToPath(newPath);

    AssertJUnit.assertEquals("distance", -0d, result.getMean().getElement(0), 0d);
    AssertJUnit.assertEquals("velocity", -1d, result.getMean().getElement(1), 0d);
  }