public static Matrix pdist(int[][] x) {
        return pdist(x, false);
    }
@Test
    public void testPdist() {
        double[][] data = {
                {-2.1968219, -0.9559913, -0.0431738, 1.0567679, 0.3853515},
                {-1.7781325, -0.6659839, 0.9526148, -0.9460919, -0.3925300},
                {-3.9749544, -1.6219752, 0.9094410, 0.1106760, -0.0071785}
        };

        Matrix d = MathEx.pdist(data);
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                assertEquals(MathEx.distance(data[i], data[j]), d.get(i, j), 1E-10);
            }
        }
    }