***** Constructing a dense matrix
      SUBROUTINE denseMatrixConstruct(iA, Al, M_print)
      COMMON /size/ N, kol_offdiag

      DIMENSION iA(*), Al(*), M_print(*)

      DO i = 1, N
        len = iA(i + 1)- iA(i) - 1
        M_print((i - 1) * (N + 1) + 1) = Al(iA(i) + len)
      END DO

      DO i = 1, N
        i_start = i - (iA(i + 1) - 1)
        DO j = iA(i), iA(i + 1) - 2
          k = i_start + j

          M_print((i - 1) * N + (k - 1) + 1) = Al(j)
          M_print((k - 1) * N + (i - 1) + 1) = Al(j)
        END DO
      END DO

      OPEN(1, FILE = 'matrix_rec.txt')
      DO i = 1, N
        DO j = 1, N
          val = M_print((i - 1) * N + j)
          WRITE(1, 100) val
        END DO
        WRITE(1, 200)
      END DO
      CLOSE(1)
      PRINT *, 'Matrix reconstruction success'
      RETURN

100   FORMAT(F5.1\, ' ')
200   FORMAT(/1x\)
      END