@Test
public void testCov_double_array() {
logger.info("\ntesting cov(double[] x, double[] y)");
assertEquals(Double.NaN, MathUtil.cov(null, null), 0.0);
assertEquals(Double.NaN, MathUtil.cov(new double[0], null), 0.0);
assertEquals(Double.NaN, MathUtil.cov(new double[] {1.0, 2.0}, null), 0.0);
assertEquals(Double.NaN, MathUtil.cov(null, new double[] {1.0, 2.0}), 0.0);
assertEquals(Double.NaN, MathUtil.cov(null, new double[0]), 0.0);
assertEquals(Double.NaN, MathUtil.cov(new double[] {1, 2}, new double[] {1, 2, 3}), 0.0);
assertEquals(0.5, MathUtil.cov(new double[] {1, 2}, new double[] {1, 2}), 0.0);
}
