public virtual void test_mapWithIndex()
        {
            double[][] @base = new double[][]
            {
                new double[] { 1d, 2d },
                new double[] { 3d, 4d },
                new double[] { 5d, 6d }
            };
            DoubleMatrix test = DoubleMatrix.copyOf(@base);

            assertMatrix(test.mapWithIndex((i, j, v) => i * (j + 1) * v), 0d, 0d, 3d, 8d, 10d, 24d);
        }