MatrixUtils { public static double[] sumRows(DoubleMatrix2D A, double[] sums) { if (sums == null || A.rows() != sums.length) { sums = new double[A.rows()]; } else { Arrays.fill(sums, 0); } for (int r = 0; r < A.rows(); r++) { for (int c = 0; c < A.columns(); c++) { sums[r] += A.getQuick(r, c); } } return sums; }  static DoubleMatrix2D normalizeColumnL2(DoubleMatrix2D A, double[] work); static DoubleMatrix2D normalizeSparseColumnL2(
      final DoubleMatrix2D A, final double[] work); static DoubleMatrix2D normalizeColumnL1(DoubleMatrix2D A, double[] work); static double computeOrthogonality(DoubleMatrix2D A); static double computeSparseness(DoubleMatrix2D A); static int[] minInColumns(DoubleMatrix2D A, int[] indices, double[] minValues); static int[] maxInColumns(DoubleMatrix2D A, int[] indices, double[] maxValues); static int[] maxInColumns(
      DoubleMatrix2D A, int[] indices, double[] maxValues, DoubleFunction transform); static int maxInRow(DoubleMatrix2D A, int row); static double[] sumRows(DoubleMatrix2D A, double[] sums); static double frobeniusNorm(DoubleMatrix2D matrix); static DoubleMatrix2D sortedRowsView(
      DoubleMatrix2D matrix, IndirectComparator comparator);  }
@Test public void testSumRows() { assertThat(MatrixUtils.sumRows(nonZeroColumnMatrix(), null)) .isEqualTo(new double[] {11, 21.5, 3}); }