### Question:
Bivariate { public static DataTable2D covarianceMatrix(Dataframe dataSet) { return bivariateMatrix(dataSet, Bivariate.BivariateType.COVARIANCE); }  static DataTable2D covarianceMatrix(Dataframe dataSet); static DataTable2D pearsonMatrix(Dataframe dataSet); static DataTable2D spearmanMatrix(Dataframe dataSet); static DataTable2D kendalltauMatrix(Dataframe dataSet);  }### Answer:
@Test public void testCovarianceMatrix() { logger.info("covarianceMatrix"); Configuration configuration = getConfiguration(); Dataframe dataset = generateDataset(configuration); DataTable2D expResult = new DataTable2D(); expResult.put2d(0, 0, 4.5625); expResult.put2d(0, 1, 0.5875); expResult.put2d(0, 2, -2.7); expResult.put2d(0, 3, -2.2041666666667); expResult.put2d(1, 0, 0.5875); expResult.put2d(1, 1, 2.1958333333333); expResult.put2d(1, 2, -0.43333333333333); expResult.put2d(1, 3, -0.3125); expResult.put2d(2, 0, -2.7); expResult.put2d(2, 1, -0.43333333333333); expResult.put2d(2, 2, 4.0); expResult.put2d(2, 3, 3.0333333333333); expResult.put2d(3, 0, -2.2041666666667); expResult.put2d(3, 1, -0.3125); expResult.put2d(3, 2, 3.0333333333333); expResult.put2d(3, 3, 3.1625); DataTable2D result = Bivariate.covarianceMatrix(dataset); TestUtils.assertDoubleDataTable2D(expResult, result); dataset.close(); }