beach_kernel_build Function

  integer(c_int) function beach_kernel_build( &
    handle, nsrc, src_pos_ptr, theta, leaf_max, order, softening, use_periodic2, periodic_axes_ptr, &
    periodic_len_ptr, image_layers, far_correction, ewald_alpha, ewald_layers, box_min_ptr, box_max_ptr &
    ) bind(C, name='beach_kernel_build') result(status)
    type(c_ptr), value :: handle
    integer(c_int), value :: nsrc
    type(c_ptr), value :: src_pos_ptr
    real(c_double), value :: theta
    integer(c_int), value :: leaf_max
    integer(c_int), value :: order
    real(c_double), value :: softening
    integer(c_int), value :: use_periodic2
    type(c_ptr), value :: periodic_axes_ptr
    type(c_ptr), value :: periodic_len_ptr
    integer(c_int), value :: image_layers
    integer(c_int), value :: far_correction
    real(c_double), value :: ewald_alpha
    integer(c_int), value :: ewald_layers
    type(c_ptr), value :: box_min_ptr
    type(c_ptr), value :: box_max_ptr

    type(field_kernel_handle), pointer :: kernel
    real(c_double), pointer :: src_pos(:, :)
    integer(c_int), pointer :: periodic_axes(:)
    real(c_double), pointer :: periodic_len(:)
    real(c_double), pointer :: box_min(:)
    real(c_double), pointer :: box_max(:)
    type(fmm_options_type) :: options

    status = get_kernel(handle, kernel)
    if (status /= beach_kernel_ok) return
    if (nsrc <= 0_c_int .or. .not. c_associated(src_pos_ptr)) then
      status = beach_kernel_invalid_argument
      return
    end if
    if (theta <= 0.0_c_double .or. leaf_max <= 0_c_int .or. order < 0_c_int .or. softening < 0.0_c_double) then
      status = beach_kernel_invalid_argument
      return
    end if

    call c_f_pointer(src_pos_ptr, src_pos, [3, int(nsrc)])
    options%theta = real(theta, dp)
    options%leaf_max = int(leaf_max, i32)
    options%order = int(order, i32)
    options%softening = real(softening, dp)

    if (use_periodic2 /= 0_c_int) then
      if (.not. c_associated(periodic_axes_ptr) .or. .not. c_associated(periodic_len_ptr) .or. &
          .not. c_associated(box_min_ptr) .or. .not. c_associated(box_max_ptr)) then
        status = beach_kernel_invalid_argument
        return
      end if
      if (image_layers < 0_c_int .or. ewald_layers < 0_c_int .or. ewald_alpha < 0.0_c_double) then
        status = beach_kernel_invalid_argument
        return
      end if
      call c_f_pointer(periodic_axes_ptr, periodic_axes, [2])
      call c_f_pointer(periodic_len_ptr, periodic_len, [2])
      call c_f_pointer(box_min_ptr, box_min, [3])
      call c_f_pointer(box_max_ptr, box_max, [3])
      if (any(periodic_axes < 1_c_int) .or. any(periodic_axes > 3_c_int) .or. &
          periodic_axes(1) == periodic_axes(2) .or. any(periodic_len <= 0.0_c_double) .or. &
          any(box_max <= box_min)) then
        status = beach_kernel_invalid_argument
        return
      end if
      options%use_periodic2 = .true.
      options%periodic_axes = int(periodic_axes, i32)
      options%periodic_len = real(periodic_len, dp)
      options%periodic_image_layers = int(image_layers, i32)
      options%periodic_ewald_alpha = real(ewald_alpha, dp)
      options%periodic_ewald_layers = int(ewald_layers, i32)
      options%target_box_min = real(box_min, dp)
      options%target_box_max = real(box_max, dp)
      select case (far_correction)
      case (0_c_int)
        options%periodic_far_correction = 'auto'
      case (1_c_int)
        options%periodic_far_correction = 'none'
      case (2_c_int)
        options%periodic_far_correction = 'm2l_root_oracle'
      case default
        status = beach_kernel_invalid_argument
        return
      end select
    end if

    if (kernel%charged) call destroy_state(kernel%state)
    if (kernel%built) call destroy_plan(kernel%plan)
    call build_plan(kernel%plan, real(src_pos, dp), options)
    kernel%built = .true.
    kernel%charged = .false.
    status = beach_kernel_ok
  end function beach_kernel_build