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); }