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module warpx_ES_solve_E_nodal
use iso_c_binding
use amrex_fort_module, only : amrex_real
implicit none
contains
! This routine computes the node-centered electric field given a node-centered phi.
! The gradient is computed using 2nd-order centered differences. It assumes the
! Boundary conditions have already been set and that you have two rows of ghost cells
! for phi and one row of ghost cells for Ex, Ey, and Ez.
! Note that this routine includes the minus sign in E = - grad phi.
!
! Arguments:
! lo, hi: The corners of the valid box over which the gradient is taken
! Ex, Ey, Ez: The electric field in the x, y, and z directions.
! dx: The cell spacing
!
subroutine warpx_compute_E_nodal_3d (lo, hi, phi, Ex, Ey, Ez, dx) &
bind(c,name='warpx_compute_E_nodal_3d')
integer(c_int), intent(in) :: lo(3), hi(3)
real(amrex_real), intent(in) :: dx(3)
real(amrex_real), intent(in ) :: phi(lo(1)-2:hi(1)+2,lo(2)-2:hi(2)+2,lo(3)-2:hi(3)+2)
real(amrex_real), intent(inout) :: Ex (lo(1)-1:hi(1)+1,lo(2)-1:hi(2)+1,lo(3)-1:hi(3)+1)
real(amrex_real), intent(inout) :: Ey (lo(1)-1:hi(1)+1,lo(2)-1:hi(2)+1,lo(3)-1:hi(3)+1)
real(amrex_real), intent(inout) :: Ez (lo(1)-1:hi(1)+1,lo(2)-1:hi(2)+1,lo(3)-1:hi(3)+1)
integer :: i, j, k
real(amrex_real) :: fac(3)
fac = 0.5d0 / dx
do k = lo(3)-1, hi(3)+1
do j = lo(2)-1, hi(2)+1
do i = lo(1)-1, hi(1)+1
Ex(i,j,k) = fac(1) * (phi(i-1,j,k) - phi(i+1,j,k))
Ey(i,j,k) = fac(2) * (phi(i,j-1,k) - phi(i,j+1,k))
Ez(i,j,k) = fac(3) * (phi(i,j,k-1) - phi(i,j,k+1))
end do
end do
end do
end subroutine warpx_compute_E_nodal_3d
subroutine warpx_compute_E_nodal_2d (lo, hi, phi, Ex, Ey, dx) &
bind(c,name='warpx_compute_E_nodal_2d')
integer(c_int), intent(in) :: lo(2), hi(2)
real(amrex_real), intent(in) :: dx(2)
real(amrex_real), intent(in ) :: phi(lo(1)-2:hi(1)+2,lo(2)-2:hi(2)+2)
real(amrex_real), intent(inout) :: Ex (lo(1)-1:hi(1)+1,lo(2)-1:hi(2)+1)
real(amrex_real), intent(inout) :: Ey (lo(1)-1:hi(1)+1,lo(2)-1:hi(2)+1)
integer :: i, j
real(amrex_real) :: fac(2)
fac = 0.5d0 / dx
do j = lo(2)-1, hi(2)+1
do i = lo(1)-1, hi(1)+1
Ex(i,j) = fac(1) * (phi(i-1,j) - phi(i+1,j))
Ey(i,j) = fac(2) * (phi(i,j-1) - phi(i,j+1))
end do
end do
end subroutine warpx_compute_E_nodal_2d
end module warpx_ES_solve_E_nodal
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