code: public static RealMatrix rbind (RealMatrix m1, RealMatrix m2) {
          return MatrixUtils.createRealMatrix(ArrayUtils.addAll(m1.getData(), m2.getData()));
      }
docs: Appends to matrices by rows.
  
  @param m1 The first matrix
  @param m2 The second matrix.
  @return Returns the new row-bound matrix.