--- /dev/null
+
+c---------------------------------------------------------------------
+c---------------------------------------------------------------------
+
+ subroutine initialize
+
+c---------------------------------------------------------------------
+c---------------------------------------------------------------------
+
+c---------------------------------------------------------------------
+c This subroutine initializes the field variable u using
+c tri-linear transfinite interpolation of the boundary values
+c---------------------------------------------------------------------
+
+ include 'header.h'
+
+ integer c, i, j, k, m, ii, jj, kk, ix, iy, iz
+ double precision xi, eta, zeta, Pface(5,3,2), Pxi, Peta,
+ > Pzeta, temp(5)
+
+
+c---------------------------------------------------------------------
+c Later (in compute_rhs) we compute 1/u for every element. A few of
+c the corner elements are not used, but it convenient (and faster)
+c to compute the whole thing with a simple loop. Make sure those
+c values are nonzero by initializing the whole thing here.
+c---------------------------------------------------------------------
+ do c = 1, ncells
+ do kk = -1, IMAX
+ do jj = -1, IMAX
+ do ii = -1, IMAX
+ u(ii, jj, kk, 1, c) = 1.0
+ u(ii, jj, kk, 2, c) = 0.0
+ u(ii, jj, kk, 3, c) = 0.0
+ u(ii, jj, kk, 4, c) = 0.0
+ u(ii, jj, kk, 5, c) = 1.0
+ end do
+ end do
+ end do
+ end do
+
+c---------------------------------------------------------------------
+c first store the "interpolated" values everywhere on the grid
+c---------------------------------------------------------------------
+ do c=1, ncells
+ kk = 0
+ do k = cell_low(3,c), cell_high(3,c)
+ zeta = dble(k) * dnzm1
+ jj = 0
+ do j = cell_low(2,c), cell_high(2,c)
+ eta = dble(j) * dnym1
+ ii = 0
+ do i = cell_low(1,c), cell_high(1,c)
+ xi = dble(i) * dnxm1
+
+ do ix = 1, 2
+ call exact_solution(dble(ix-1), eta, zeta,
+ > Pface(1,1,ix))
+ end do
+
+ do iy = 1, 2
+ call exact_solution(xi, dble(iy-1) , zeta,
+ > Pface(1,2,iy))
+ end do
+
+ do iz = 1, 2
+ call exact_solution(xi, eta, dble(iz-1),
+ > Pface(1,3,iz))
+ end do
+
+ do m = 1, 5
+ Pxi = xi * Pface(m,1,2) +
+ > (1.0d0-xi) * Pface(m,1,1)
+ Peta = eta * Pface(m,2,2) +
+ > (1.0d0-eta) * Pface(m,2,1)
+ Pzeta = zeta * Pface(m,3,2) +
+ > (1.0d0-zeta) * Pface(m,3,1)
+
+ u(ii,jj,kk,m,c) = Pxi + Peta + Pzeta -
+ > Pxi*Peta - Pxi*Pzeta - Peta*Pzeta +
+ > Pxi*Peta*Pzeta
+
+ end do
+ ii = ii + 1
+ end do
+ jj = jj + 1
+ end do
+ kk = kk+1
+ end do
+ end do
+
+c---------------------------------------------------------------------
+c now store the exact values on the boundaries
+c---------------------------------------------------------------------
+
+c---------------------------------------------------------------------
+c west face
+c---------------------------------------------------------------------
+ c = slice(1,1)
+ ii = 0
+ xi = 0.0d0
+ kk = 0
+ do k = cell_low(3,c), cell_high(3,c)
+ zeta = dble(k) * dnzm1
+ jj = 0
+ do j = cell_low(2,c), cell_high(2,c)
+ eta = dble(j) * dnym1
+ call exact_solution(xi, eta, zeta, temp)
+ do m = 1, 5
+ u(ii,jj,kk,m,c) = temp(m)
+ end do
+ jj = jj + 1
+ end do
+ kk = kk + 1
+ end do
+
+c---------------------------------------------------------------------
+c east face
+c---------------------------------------------------------------------
+ c = slice(1,ncells)
+ ii = cell_size(1,c)-1
+ xi = 1.0d0
+ kk = 0
+ do k = cell_low(3,c), cell_high(3,c)
+ zeta = dble(k) * dnzm1
+ jj = 0
+ do j = cell_low(2,c), cell_high(2,c)
+ eta = dble(j) * dnym1
+ call exact_solution(xi, eta, zeta, temp)
+ do m = 1, 5
+ u(ii,jj,kk,m,c) = temp(m)
+ end do
+ jj = jj + 1
+ end do
+ kk = kk + 1
+ end do
+
+c---------------------------------------------------------------------
+c south face
+c---------------------------------------------------------------------
+ c = slice(2,1)
+ jj = 0
+ eta = 0.0d0
+ kk = 0
+ do k = cell_low(3,c), cell_high(3,c)
+ zeta = dble(k) * dnzm1
+ ii = 0
+ do i = cell_low(1,c), cell_high(1,c)
+ xi = dble(i) * dnxm1
+ call exact_solution(xi, eta, zeta, temp)
+ do m = 1, 5
+ u(ii,jj,kk,m,c) = temp(m)
+ end do
+ ii = ii + 1
+ end do
+ kk = kk + 1
+ end do
+
+
+c---------------------------------------------------------------------
+c north face
+c---------------------------------------------------------------------
+ c = slice(2,ncells)
+ jj = cell_size(2,c)-1
+ eta = 1.0d0
+ kk = 0
+ do k = cell_low(3,c), cell_high(3,c)
+ zeta = dble(k) * dnzm1
+ ii = 0
+ do i = cell_low(1,c), cell_high(1,c)
+ xi = dble(i) * dnxm1
+ call exact_solution(xi, eta, zeta, temp)
+ do m = 1, 5
+ u(ii,jj,kk,m,c) = temp(m)
+ end do
+ ii = ii + 1
+ end do
+ kk = kk + 1
+ end do
+
+c---------------------------------------------------------------------
+c bottom face
+c---------------------------------------------------------------------
+ c = slice(3,1)
+ kk = 0
+ zeta = 0.0d0
+ jj = 0
+ do j = cell_low(2,c), cell_high(2,c)
+ eta = dble(j) * dnym1
+ ii = 0
+ do i =cell_low(1,c), cell_high(1,c)
+ xi = dble(i) *dnxm1
+ call exact_solution(xi, eta, zeta, temp)
+ do m = 1, 5
+ u(ii,jj,kk,m,c) = temp(m)
+ end do
+ ii = ii + 1
+ end do
+ jj = jj + 1
+ end do
+
+c---------------------------------------------------------------------
+c top face
+c---------------------------------------------------------------------
+ c = slice(3,ncells)
+ kk = cell_size(3,c)-1
+ zeta = 1.0d0
+ jj = 0
+ do j = cell_low(2,c), cell_high(2,c)
+ eta = dble(j) * dnym1
+ ii = 0
+ do i =cell_low(1,c), cell_high(1,c)
+ xi = dble(i) * dnxm1
+ call exact_solution(xi, eta, zeta, temp)
+ do m = 1, 5
+ u(ii,jj,kk,m,c) = temp(m)
+ end do
+ ii = ii + 1
+ end do
+ jj = jj + 1
+ end do
+
+ return
+ end
+
+
+ subroutine lhsinit
+
+ include 'header.h'
+
+ integer i, j, k, d, c, n
+
+c---------------------------------------------------------------------
+c loop over all cells
+c---------------------------------------------------------------------
+ do c = 1, ncells
+
+c---------------------------------------------------------------------
+c first, initialize the start and end arrays
+c---------------------------------------------------------------------
+ do d = 1, 3
+ if (cell_coord(d,c) .eq. 1) then
+ start(d,c) = 1
+ else
+ start(d,c) = 0
+ endif
+ if (cell_coord(d,c) .eq. ncells) then
+ end(d,c) = 1
+ else
+ end(d,c) = 0
+ endif
+ end do
+
+c---------------------------------------------------------------------
+c zap the whole left hand side for starters
+c---------------------------------------------------------------------
+ do n = 1, 15
+ do k = 0, cell_size(3,c)-1
+ do j = 0, cell_size(2,c)-1
+ do i = 0, cell_size(1,c)-1
+ lhs(i,j,k,n,c) = 0.0d0
+ end do
+ end do
+ end do
+ end do
+
+c---------------------------------------------------------------------
+c next, set all diagonal values to 1. This is overkill, but convenient
+c---------------------------------------------------------------------
+ do n = 1, 3
+ do k = 0, cell_size(3,c)-1
+ do j = 0, cell_size(2,c)-1
+ do i = 0, cell_size(1,c)-1
+ lhs(i,j,k,5*n-2,c) = 1.0d0
+ end do
+ end do
+ end do
+ end do
+
+ end do
+
+ return
+ end
+
+
+
