| function df_dx(this) |
| implicit none |
| class(tensor), intent(in):: this |
| type(tensor):: df_dx |
| integer(ikind):: i, nx |
| real(c_double):: dx, left_image, right_image |
| real(c_double), dimension(:), allocatable, save:: local_tensor_data |
| nx = local_grid_resolution |
| if (.not.allocated(local_tensor_data)) allocate(local_tensor_data(nx)) |
| dx = 2. pi/(real(nx, c_double) num_procs) |
| if (num_procs > 1) then |
| call MPI_SENDRECV(this%global_f(), 1, |
| MPI_DOUBLE_PRECISION, left_id, 0, right_image, 1, |
| MPI_DOUBLE_PRECISION, right_id, 0, MPI_COMM_CART, |
| status, ierr) |
| call MPI_SENDRECV(this%global_f(nx), 1, |
| MPI_DOUBLE_PRECISION, right_id, 0, left_image, 1, |
| MPI_DOUBLE_PRECISION, left_id, 0, MPI_COMM_CART, |
| status, ierr) |
| else |
| left_image = this%global_f(nx) |
| right_image = this%global_f() |
| end if |
| local_tensor_data() = 0.5 (this%global_f() − left_image)/dx |
| local_tensor_data(nx) = 0.5 (right_image − this%global_f(nx − 1))/dx |
| do concurrent(i = 2 : nx − 1) |
| local_tensor_data(i) = 0.5 (this%global_f(i + 1) − this%global_f(i − 1))/dx |
| end do |
| df_dx%global_f = local_tensor_data |
| end function |
