创建矩阵如何使用并行计算

739977719 · 发表于 2022-5-8 10:12:28

  !===========================================
  ! A subroutine for assembling Laplace matrix
  ! in the compressed row storage format
  ! (sequential version)
  !===========================================
  use header
  implicit none

  ! Variables as per assignment
  integer, intent(in) :: m
  type(Matrix), intent(inout) :: Delta

  ! Loop counters: total, horizontal, vertical, nonzeros, neighbour
  integer ::    irow,  i,       j,       inz,    next
  ! Total problem size
  integer :: n

  n = m*m
  Delta%n = n

  allocate(Delta%ii(n+1))
  allocate(Delta%aa(5*n))
  allocate(Delta%jj(5*n))

  inz = 1 ! index of current nonzero element
  do irow=1,n
   ! Calculate Cartesian index splitting
   j = (irow-1)/m + 1
   i = irow - (j-1)*m

   ! Init current row position
   Delta%ii(irow) = inz

   ! Diagonal element
   Delta%aa(inz) = -4.0_rk * m**2 ! -4/h^2
   Delta%jj(inz) = irow          ! column index = row index on diagonal
   ! Done with diagonal element, shift the counter of elements
   inz = inz + 1

   ! Off-diagonal elements, including periodically looped ones
   ! left
   Delta%aa(inz) = m**2          ! 1/h^2
   next = i-1
   if (next<1) next = m          ! loop over if we are on a boundary
   Delta%jj(inz) = next + (j-1)*m ! column index back in global range
   ! shift the nnz counter
   inz = inz + 1

   ! right
   Delta%aa(inz) = m**2
   next = i+1
   if (next>m) next = 1
   Delta%jj(inz) = next + (j-1)*m
   inz = inz + 1

   ! bottom
   Delta%aa(inz) = m**2
   next = j-1
   if (next<1) next = m
   Delta%jj(inz) = i + (next-1)*m
   inz = inz + 1

   ! top
   Delta%aa(inz) = m**2
   next = j+1
   if (next>m) next = 1
   Delta%jj(inz) = i + (next-1)*m
   inz = inz + 1
  end do

  ! Finalise row positions
  Delta%ii(irow) = inz
  Delta%nnz = inz-1

end subroutine create_matrix

这是一个创建矩阵的子程序，请问怎么写mpi并行计算

[线性代数] 创建矩阵如何使用并行计算