Optimised 8-4 derivative operators. Experimental 8-4 dissipation operators.

Tests of these are on going.


git-svn-id: https://svn.cct.lsu.edu/repos/numrel/LSUThorns/SummationByParts/trunk@32 f69c4107-0314-4c4f-9ad4-17e986b73f4a

5 files changed, 995 insertions, 31 deletions

diff --git a/src/Derivatives_8_4_min_err_coeff.F90 b/src/Derivatives_8_4_min_err_coeff.F90
new file mode 100644
index 0000000..a06ee18
--- /dev/null
+++ b/src/Derivatives_8_4_min_err_coeff.F90
@@ -0,0 +1,423 @@
+#include "cctk.h"
+#include "cctk_Functions.h"
+#include "cctk_Parameters.h"
+
+subroutine deriv_gf_8_4_opt ( var, ni, nj, nk, dir, bb, gsize, delta, dvar )
+
+  implicit none
+
+  DECLARE_CCTK_FUNCTIONS
+  DECLARE_CCTK_PARAMETERS
+
+  CCTK_REAL, parameter :: zero = 0.0
+  integer, parameter :: wp = kind(zero)
+  CCTK_INT, intent(IN) :: ni, nj, nk
+  CCTK_REAL, dimension(ni,nj,nk), intent(IN) :: var
+  CCTK_INT, intent(IN) :: dir
+  CCTK_INT, intent(IN) :: bb(2)
+  CCTK_INT, intent(IN) :: gsize
+  CCTK_REAL, intent(IN) :: delta
+  CCTK_REAL, dimension(ni,nj,nk), intent(OUT) :: dvar
+
+  CCTK_REAL, dimension(4), save :: a
+  CCTK_REAL, dimension(12,8), save :: q 
+  CCTK_REAL :: idel
+
+  CCTK_INT :: il, ir, jl, jr, kl, kr, j, k
+
+  logical, save :: first = .true.
+
+  if ( first ) then
+    a(1) = 4.0_wp/5.0_wp; a(2) = -1.0_wp/5.0_wp
+    a(3) = 4.0_wp/105.0_wp; a(4) = -1.0_wp/280.0_wp
+
+    q(1,1) = -1.695543604431898508749855654248370812054_wp
+    q(2,1) = 2.244525109969933844775276252674718713114_wp
+    q(3,1) = -0.002163206607021876385102025416828692597556_wp
+    q(4,1) = -0.8963677947307838167920190976769921451579_wp
+    q(5,1) = 0.2272938673777916084251861567415263328923_wp
+    q(6,1) = 0.1564962758424078514454013191006671546757_wp
+    q(7,1) = 0.003067629343740613524557473056482141287158_wp
+    q(8,1) = -0.03730827676416971624344442423120269215938_wp
+    q(9,1) = 0_wp
+    q(10,1) = 0_wp
+    q(11,1) = 0_wp
+    q(12,1) = 0_wp
+    q(1,2) = -0.4338209217401506177055540526837828066711_wp
+    q(2,2) = 0_wp
+    q(3,2) = 0.06631961192627293470305188523936353462439_wp
+    q(4,2) = 0.6021342012739069461791324177355805603656_wp
+    q(5,2) = -0.2213339967864188453859900127368926875520_wp
+    q(6,2) = -0.001759980003751516130708214237001705688807_wp
+    q(7,2) = -0.03586646217917856587352426166797879385310_wp
+    q(8,2) = 0.02432754750931966421359223835071189877503_wp
+    q(9,2) = 0_wp
+    q(10,2) = 0_wp
+    q(11,2) = 0_wp
+    q(12,2) = 0_wp
+    q(1,3) = 0.002477771724790106958560398469919805908522_wp
+    q(2,3) = -0.3930241559935857537756812928554282732813_wp
+    q(3,3) = 0_wp
+    q(4,3) = -0.6080263371305341035810612202824357742461_wp
+    q(5,3) = 2.372533124692864412954923458457782022478_wp
+    q(6,3) = -2.126112217612194556872952028715623246817_wp
+    q(7,3) = 0.9075309435559160631495435310307745215131_wp
+    q(8,3) = -0.1553791292372561688333328461049890555549_wp
+    q(9,3) = 0_wp
+    q(10,3) = 0_wp
+    q(11,3) = 0_wp
+    q(12,3) = 0_wp
+    q(1,4) = 0.1470043328582935680963279007411074464266_wp
+    q(2,4) = -0.5109179516689331400658365102850902594996_wp
+    q(3,4) = 0.08705685833207777685654755900085198684605_wp
+    q(4,4) = 0_wp
+    q(5,4) = -0.1306945333157231839535552435788086367322_wp
+    q(6,4) = 0.5981933016362239542598518794410035592720_wp
+    q(7,4) = -0.2031099149801233772210520666270517105660_wp
+    q(8,4) = 0.01246790713818440202771648130798761425319_wp
+    q(9,4) = 0_wp
+    q(10,4) = 0_wp
+    q(11,4) = 0_wp
+    q(12,4) = 0_wp
+    q(1,5) = -0.1624073990846984662267508265053107632238_wp
+    q(2,5) = 0.8182390368133059538132603839842499379861_wp
+    q(3,5) = -1.480018301574606037840376638130713134769_wp
+    q(4,5) = 0.5694185675497882973361521309100738568707_wp
+    q(5,5) = 0_wp
+    q(6,5) = 0.02929508293831017534661096502884570435894_wp
+    q(7,5) = 0.2825910005984090924748504462528740123097_wp
+    q(8,5) = -0.04846434332860791750685068920563907354793_wp
+    q(9,5) = -0.008653643911901097396895772334380539984709_wp
+    q(10,5) = 0_wp
+    q(11,5) = 0_wp
+    q(12,5) = 0_wp
+    q(1,6) = -0.03609686950604370828405582087760384548297_wp
+    q(2,6) = 0.002100328577309696555612805397001149641337_wp
+    q(3,6) = 0.4281425817419204360479874008765051769418_wp
+    q(4,6) = -0.8413238238875046736839550701643761633826_wp
+    q(5,6) = -0.009456755727630000971085851751473603919416_wp
+    q(6,6) = 0_wp
+    q(7,6) = 0.5172389789041733771234394082779034212042_wp
+    q(8,6) = -0.08760813565107717873901807278223424202774_wp
+    q(9,6) = 0.02979718129528502284256573906127239395909_wp
+    q(10,6) = -0.002793485746432970891490538036994286933664_wp
+    q(11,6) = 0_wp
+    q(12,6) = 0_wp
+    q(1,7) = -0.0009797678134978722516935350416937185004514_wp
+    q(2,7) = 0.05926834509975463070197111976550139351983_wp
+    q(3,7) = -0.2530570463899371286637621744353665227114_wp
+    q(4,7) = 0.3955555826583941989223787901885502942688_wp
+    q(5,7) = -0.1263166266018192756531792392597193430222_wp
+    q(6,7) = -0.7162192643577544899896537844517283192029_wp
+    q(7,7) = 0_wp
+    q(8,7) = 0.8209721963136350137518635528607308559584_wp
+    q(9,7) = -0.2166153552278720352907291696202456084323_wp
+    q(10,7) = 0.04126006766245181624585317516576106827282_wp
+    q(11,7) = -0.003868131343354857773048735171790100150577_wp
+    q(12,7) = 0_wp
+    q(1,8) = 0.01090012273307913185972171872891927027272_wp
+    q(2,8) = -0.03677379943661633440187210478144113487019_wp
+    q(3,8) = 0.03963287609450569641558898819403594845401_wp
+    q(4,8) = -0.02221139656912423686782339404035534965598_wp
+    q(5,8) = 0.01981665906734246925389947980969432794418_wp
+    q(6,8) = 0.1109698768905366566973791789571759073485_wp
+    q(7,8) = -0.7509903604688148129224205834189298636300_wp
+    q(8,8) = 0_wp
+    q(9,8) = 0.7926019635554773751160111698352821779736_wp
+    q(10,8) = -0.1981504908888693437790027924588205444934_wp
+    q(11,8) = 0.03774295064549892262457196046834677037969_wp
+    q(12,8) = -0.003538401623015523996053621293907509723096_wp
+
+    first = .false. 
+  end if
+
+  idel = 1.0_wp / delta
+
+  direction: select case (dir)
+  case (0) direction
+    if ( bb(1) == 0 ) then
+      il = 1 + gsize
+    else
+      dvar(1,:,:) = ( q(1,1) * var(1,:,:) + q(2,1) * var(2,:,:) + &
+                      q(3,1) * var(3,:,:) + q(4,1) * var(4,:,:) + &
+                      q(5,1) * var(5,:,:) + q(6,1) * var(6,:,:) + &
+                      q(7,1) * var(7,:,:) + q(8,1) * var(8,:,:) ) * idel
+      dvar(2,:,:) = ( q(1,2) * var(1,:,:) + q(3,2) * var(3,:,:) + &
+                      q(4,2) * var(4,:,:) + q(5,2) * var(5,:,:) + &
+                      q(6,2) * var(6,:,:) + q(7,2) * var(7,:,:) + &
+                      q(8,2) * var(8,:,:) ) * idel
+      dvar(3,:,:) = ( q(1,3) * var(1,:,:) + q(2,3) * var(2,:,:) + &
+                      q(4,3) * var(4,:,:) + q(5,3) * var(5,:,:) + &
+                      q(6,3) * var(6,:,:) + q(7,3) * var(7,:,:) + &
+                      q(8,3) * var(8,:,:) ) * idel
+      dvar(4,:,:) = ( q(1,4) * var(1,:,:) + q(2,4) * var(2,:,:) + &
+                      q(3,4) * var(3,:,:) + q(5,4) * var(5,:,:) + &
+                      q(6,4) * var(6,:,:) + q(7,4) * var(7,:,:) + &
+                      q(8,4) * var(8,:,:) ) * idel
+      dvar(5,:,:) = ( q(1,5) * var(1,:,:) + q(2,5) * var(2,:,:) + &
+                      q(3,5) * var(3,:,:) + q(4,5) * var(4,:,:) + &
+                      q(6,5) * var(6,:,:) + q(7,5) * var(7,:,:) + &
+                      q(8,5) * var(8,:,:) + q(9,5) * var(9,:,:) ) * idel
+      dvar(6,:,:) = ( q(1,6) * var(1,:,:) + q(2,6) * var(2,:,:) + &
+                      q(3,6) * var(3,:,:) + q(4,6) * var(4,:,:) + &
+                      q(5,6) * var(5,:,:) + q(7,6) * var(7,:,:) + &
+                      q(8,6) * var(8,:,:) + q(9,6) * var(9,:,:) + &
+                      q(10,6) * var(10,:,:) ) * idel
+      dvar(7,:,:) = ( q(1,7) * var(1,:,:) + q(2,7) * var(2,:,:) + &
+                      q(3,7) * var(3,:,:) + q(4,7) * var(4,:,:) + &
+                      q(5,7) * var(5,:,:) + q(6,7) * var(6,:,:) + &
+                      q(8,7) * var(8,:,:) + q(9,7) * var(9,:,:) + &
+                      q(10,7) * var(10,:,:) + q(11,7) * var(11,:,:) ) * idel
+      dvar(8,:,:) = ( q(1,8) * var(1,:,:) + q(2,8) * var(2,:,:) + &
+                      q(3,8) * var(3,:,:) + q(4,8) * var(4,:,:) + &
+                      q(5,8) * var(5,:,:) + q(6,8) * var(6,:,:) + &
+                      q(7,8) * var(7,:,:) + q(9,8) * var(9,:,:) + &
+                      q(10,8) * var(10,:,:) + q(11,8) * var(11,:,:) + &
+                      q(12,8) * var(12,:,:) ) * idel
+      il = 9
+    end if
+    if ( bb(2) == 0 ) then
+      ir = ni - gsize
+    else
+      dvar(ni,:,:) =   - ( q(1,1) * var(ni,:,:) + q(2,1) * var(ni-1,:,:) + &
+                           q(3,1) * var(ni-2,:,:) + q(4,1) * var(ni-3,:,:) + &
+                           q(5,1) * var(ni-4,:,:) + q(6,1) * var(ni-5,:,:) + &
+                           q(7,1) * var(ni-6,:,:) + &
+                           q(8,1) * var(ni-7,:,:) ) * idel
+      dvar(ni-1,:,:) = - ( q(1,2) * var(ni,:,:) + q(3,2) * var(ni-2,:,:) + &
+                           q(4,2) * var(ni-3,:,:) + q(5,2) * var(ni-4,:,:) + &
+                           q(6,2) * var(ni-5,:,:) + q(7,2) * var(ni-6,:,:) + &
+                           q(8,2) * var(ni-7,:,:) ) * idel
+      dvar(ni-2,:,:) = - ( q(1,3) * var(ni,:,:) + q(2,3) * var(ni-1,:,:) + &
+                           q(4,3) * var(ni-3,:,:) + q(5,3) * var(ni-4,:,:) + &
+                           q(6,3) * var(ni-5,:,:) + q(7,3) * var(ni-6,:,:) + &
+                           q(8,3) * var(ni-7,:,:) ) * idel
+      dvar(ni-3,:,:) = - ( q(1,4) * var(ni,:,:) + q(2,4) * var(ni-1,:,:) + &
+                           q(3,4) * var(ni-2,:,:) + q(5,4) * var(ni-4,:,:) + &
+                           q(6,4) * var(ni-5,:,:) + q(7,4) * var(ni-6,:,:) + &
+                           q(8,4) * var(ni-7,:,:) ) * idel
+      dvar(ni-4,:,:) = - ( q(1,5) * var(ni,:,:) + q(2,5) * var(ni-1,:,:) + &
+                           q(3,5) * var(ni-2,:,:) + q(4,5) * var(ni-3,:,:) + &
+                           q(6,5) * var(ni-5,:,:) + q(7,5) * var(ni-6,:,:) + &
+                           q(8,5) * var(ni-7,:,:) + &
+                           q(9,5) * var(ni-8,:,:) ) * idel
+      dvar(ni-5,:,:) = - ( q(1,6) * var(ni,:,:) + q(2,6) * var(ni-1,:,:) + &
+                           q(3,6) * var(ni-2,:,:) + q(4,6) * var(ni-3,:,:) + &
+                           q(5,6) * var(ni-4,:,:) + q(7,6) * var(ni-6,:,:) + &
+                           q(8,6) * var(ni-7,:,:) + q(9,6) * var(ni-8,:,:) + &
+                           q(10,6) * var(ni-9,:,:) ) * idel
+      dvar(ni-6,:,:) = - ( q(1,7) * var(ni,:,:) + q(2,7) * var(ni-1,:,:) + &
+                           q(3,7) * var(ni-2,:,:) + q(4,7) * var(ni-3,:,:) + &
+                           q(5,7) * var(ni-4,:,:) + q(6,7) * var(ni-5,:,:) + &
+                           q(8,7) * var(ni-7,:,:) + q(9,7) * var(ni-8,:,:) + &
+                           q(10,7) * var(ni-9,:,:) + &
+                           q(11,7) * var(ni-10,:,:) ) * idel
+      dvar(ni-7,:,:) = - ( q(1,8) * var(ni,:,:) + q(2,8) * var(ni-1,:,:) + &
+                           q(3,8) * var(ni-2,:,:) + q(4,8) * var(ni-3,:,:) + &
+                           q(5,8) * var(ni-4,:,:) + q(6,8) * var(ni-5,:,:) + &
+                           q(7,8) * var(ni-6,:,:) + q(9,8) * var(ni-8,:,:) + &
+                           q(10,8) * var(ni-9,:,:) + &
+                           q(11,8) * var(ni-10,:,:) + &
+                           q(12,8) * var(ni-11,:,:) ) * idel
+      ir = ni - 8
+    end if
+    dvar(il:ir,:,:) = ( a(1) * ( var(il+1:ir+1,:,:) - &
+                                 var(il-1:ir-1,:,:) ) + &
+                        a(2) * ( var(il+2:ir+2,:,:) - &
+                                 var(il-2:ir-2,:,:) ) + &
+                        a(3) * ( var(il+3:ir+3,:,:) - &
+                                 var(il-3:ir-3,:,:) ) + &
+                        a(4) * ( var(il+4:ir+4,:,:) - &
+                                 var(il-4:ir-4,:,:) ) ) * idel
+  case (1) direction
+    if ( bb(1) == 0 ) then
+      jl = 1 + gsize
+    else
+      dvar(:,1,:) = ( q(1,1) * var(:,1,:) + q(2,1) * var(:,2,:) + &
+                      q(3,1) * var(:,3,:) + q(4,1) * var(:,4,:) + &
+                      q(5,1) * var(:,5,:) + q(6,1) * var(:,6,:) + &
+                      q(7,1) * var(:,7,:) + q(8,1) * var(:,8,:) ) * idel
+      dvar(:,2,:) = ( q(1,2) * var(:,1,:) + q(3,2) * var(:,3,:) + &
+                      q(4,2) * var(:,4,:) + q(5,2) * var(:,5,:) + &
+                      q(6,2) * var(:,6,:) + q(7,2) * var(:,7,:) + &
+                      q(8,2) * var(:,8,:) ) * idel
+      dvar(:,3,:) = ( q(1,3) * var(:,1,:) + q(2,3) * var(:,2,:) + &
+                      q(4,3) * var(:,4,:) + q(5,3) * var(:,5,:) + &
+                      q(6,3) * var(:,6,:) + q(7,3) * var(:,7,:) + &
+                      q(8,3) * var(:,8,:) ) * idel
+      dvar(:,4,:) = ( q(1,4) * var(:,1,:) + q(2,4) * var(:,2,:) + &
+                      q(3,4) * var(:,3,:) + q(5,4) * var(:,5,:) + &
+                      q(6,4) * var(:,6,:) + q(7,4) * var(:,7,:) + &
+                      q(8,4) * var(:,8,:) ) * idel
+      dvar(:,5,:) = ( q(1,5) * var(:,1,:) + q(2,5) * var(:,2,:) + &
+                      q(3,5) * var(:,3,:) + q(4,5) * var(:,4,:) + &
+                      q(6,5) * var(:,6,:) + q(7,5) * var(:,7,:) + &
+                      q(8,5) * var(:,8,:) + q(9,5) * var(:,9,:) ) * idel
+      dvar(:,6,:) = ( q(1,6) * var(:,1,:) + q(2,6) * var(:,2,:) + &
+                      q(3,6) * var(:,3,:) + q(4,6) * var(:,4,:) + &
+                      q(5,6) * var(:,5,:) + q(7,6) * var(:,7,:) + &
+                      q(8,6) * var(:,8,:) + q(9,6) * var(:,9,:) + &
+                      q(10,6) * var(:,10,:) ) * idel
+      dvar(:,7,:) = ( q(1,7) * var(:,1,:) + q(2,7) * var(:,2,:) + &
+                      q(3,7) * var(:,3,:) + q(4,7) * var(:,4,:) + &
+                      q(5,7) * var(:,5,:) + q(6,7) * var(:,6,:) + &
+                      q(8,7) * var(:,8,:) + q(9,7) * var(:,9,:) + &
+                      q(10,7) * var(:,10,:) + q(11,7) * var(:,11,:) ) * idel
+      dvar(:,8,:) = ( q(1,8) * var(:,1,:) + q(2,8) * var(:,2,:) + &
+                      q(3,8) * var(:,3,:) + q(4,8) * var(:,4,:) + &
+                      q(5,8) * var(:,5,:) + q(6,8) * var(:,6,:) + &
+                      q(7,8) * var(:,7,:) + q(9,8) * var(:,9,:) + &
+                      q(10,8) * var(:,10,:) + q(11,8) * var(:,11,:) + &
+                      q(12,8) * var(:,12,:) ) * idel
+      jl = 9
+    end if
+    if ( bb(2) == 0 ) then
+      jr = nj - gsize
+    else
+      dvar(:,nj,:) =   - ( q(1,1) * var(:,nj,:) + q(2,1) * var(:,nj-1,:) + &
+                           q(3,1) * var(:,nj-2,:) + q(4,1) * var(:,nj-3,:) + &
+                           q(5,1) * var(:,nj-4,:) + q(6,1) * var(:,nj-5,:) + &
+                           q(7,1) * var(:,nj-6,:) + &
+                           q(8,1) * var(:,nj-7,:) ) * idel
+      dvar(:,nj-1,:) = - ( q(1,2) * var(:,nj,:) + q(3,2) * var(:,nj-2,:) + &
+                           q(4,2) * var(:,nj-3,:) + q(5,2) * var(:,nj-4,:) + &
+                           q(6,2) * var(:,nj-5,:) + q(7,2) * var(:,nj-6,:) + &
+                           q(8,2) * var(:,nj-7,:) ) * idel
+      dvar(:,nj-2,:) = - ( q(1,3) * var(:,nj,:) + q(2,3) * var(:,nj-1,:) + &
+                           q(4,3) * var(:,nj-3,:) + q(5,3) * var(:,nj-4,:) + &
+                           q(6,3) * var(:,nj-5,:) + q(7,3) * var(:,nj-6,:) + &
+                           q(8,3) * var(:,nj-7,:) ) * idel
+      dvar(:,nj-3,:) = - ( q(1,4) * var(:,nj,:) + q(2,4) * var(:,nj-1,:) + &
+                           q(3,4) * var(:,nj-2,:) + q(5,4) * var(:,nj-4,:) + &
+                           q(6,4) * var(:,nj-5,:) + q(7,4) * var(:,nj-6,:) + &
+                           q(8,4) * var(:,nj-7,:) ) * idel
+      dvar(:,nj-4,:) = - ( q(1,5) * var(:,nj,:) + q(2,5) * var(:,nj-1,:) + &
+                           q(3,5) * var(:,nj-2,:) + q(4,5) * var(:,nj-3,:) + &
+                           q(6,5) * var(:,nj-5,:) + q(7,5) * var(:,nj-6,:) + &
+                           q(8,5) * var(:,nj-7,:) + &
+                           q(9,5) * var(:,nj-8,:) ) * idel
+      dvar(:,nj-5,:) = - ( q(1,6) * var(:,nj,:) + q(2,6) * var(:,nj-1,:) + &
+                           q(3,6) * var(:,nj-2,:) + q(4,6) * var(:,nj-3,:) + &
+                           q(5,6) * var(:,nj-4,:) + q(7,6) * var(:,nj-6,:) + &
+                           q(8,6) * var(:,nj-7,:) + q(9,6) * var(:,nj-8,:) + &
+                           q(10,6) * var(:,nj-9,:) ) * idel
+      dvar(:,nj-6,:) = - ( q(1,7) * var(:,nj,:) + q(2,7) * var(:,nj-1,:) + &
+                           q(3,7) * var(:,nj-2,:) + q(4,7) * var(:,nj-3,:) + &
+                           q(5,7) * var(:,nj-4,:) + q(6,7) * var(:,nj-5,:) + &
+                           q(8,7) * var(:,nj-7,:) + q(9,7) * var(:,nj-8,:) + &
+                           q(10,7) * var(:,nj-9,:) + &
+                           q(11,7) * var(:,nj-10,:) ) * idel
+      dvar(:,nj-7,:) = - ( q(1,8) * var(:,nj,:) + q(2,8) * var(:,nj-1,:) + &
+                           q(3,8) * var(:,nj-2,:) + q(4,8) * var(:,nj-3,:) + &
+                           q(5,8) * var(:,nj-4,:) + q(6,8) * var(:,nj-5,:) + &
+                           q(7,8) * var(:,nj-6,:) + q(9,8) * var(:,nj-8,:) + &
+                           q(10,8) * var(:,nj-9,:) + &
+                           q(11,8) * var(:,nj-10,:) + &
+                           q(12,8) * var(:,nj-11,:) ) * idel
+      jr = nj - 8
+    end if
+    dvar(:,jl:jr,:) = ( a(1) * ( var(:,jl+1:jr+1,:) - &
+                                 var(:,jl-1:jr-1,:) ) + &
+                        a(2) * ( var(:,jl+2:jr+2,:) - &
+                                 var(:,jl-2:jr-2,:) ) + &
+                        a(3) * ( var(:,jl+3:jr+3,:) - &
+                                 var(:,jl-3:jr-3,:) ) + &
+                        a(4) * ( var(:,jl+4:jr+4,:) - &
+                                 var(:,jl-4:jr-4,:) ) ) * idel
+  case (2) direction
+    if ( bb(1) == 0 ) then
+      kl = 1 + gsize
+    else
+      dvar(:,:,1) = ( q(1,1) * var(:,:,1) + q(2,1) * var(:,:,2) + &
+                      q(3,1) * var(:,:,3) + q(4,1) * var(:,:,4) + &
+                      q(5,1) * var(:,:,5) + q(6,1) * var(:,:,6) + &
+                      q(7,1) * var(:,:,7) + q(8,1) * var(:,:,8) ) * idel
+      dvar(:,:,2) = ( q(1,2) * var(:,:,1) + q(3,2) * var(:,:,3) + &
+                      q(4,2) * var(:,:,4) + q(5,2) * var(:,:,5) + &
+                      q(6,2) * var(:,:,6) + q(7,2) * var(:,:,7) + &
+                      q(8,2) * var(:,:,8) ) * idel
+      dvar(:,:,3) = ( q(1,3) * var(:,:,1) + q(2,3) * var(:,:,2) + &
+                      q(4,3) * var(:,:,4) + q(5,3) * var(:,:,5) + &
+                      q(6,3) * var(:,:,6) + q(7,3) * var(:,:,7) + &
+                      q(8,3) * var(:,:,8) ) * idel
+      dvar(:,:,4) = ( q(1,4) * var(:,:,1) + q(2,4) * var(:,:,2) + &
+                      q(3,4) * var(:,:,3) + q(5,4) * var(:,:,5) + &
+                      q(6,4) * var(:,:,6) + q(7,4) * var(:,:,7) + &
+                      q(8,4) * var(:,:,8) ) * idel
+      dvar(:,:,5) = ( q(1,5) * var(:,:,1) + q(2,5) * var(:,:,2) + &
+                      q(3,5) * var(:,:,3) + q(4,5) * var(:,:,4) + &
+                      q(6,5) * var(:,:,6) + q(7,5) * var(:,:,7) + &
+                      q(8,5) * var(:,:,8) + q(9,5) * var(:,:,9) ) * idel
+      dvar(:,:,6) = ( q(1,6) * var(:,:,1) + q(2,6) * var(:,:,2) + &
+                      q(3,6) * var(:,:,3) + q(4,6) * var(:,:,4) + &
+                      q(5,6) * var(:,:,5) + q(7,6) * var(:,:,7) + &
+                      q(8,6) * var(:,:,8) + q(9,6) * var(:,:,9) + &
+                      q(10,6) * var(:,:,10) ) * idel
+      dvar(:,:,7) = ( q(1,7) * var(:,:,1) + q(2,7) * var(:,:,2) + &
+                      q(3,7) * var(:,:,3) + q(4,7) * var(:,:,4) + &
+                      q(5,7) * var(:,:,5) + q(6,7) * var(:,:,6) + &
+                      q(8,7) * var(:,:,8) + q(9,7) * var(:,:,9) + &
+                      q(10,7) * var(:,:,10) + q(11,7) * var(:,:,11) ) * idel
+      dvar(:,:,8) = ( q(1,8) * var(:,:,1) + q(2,8) * var(:,:,2) + &
+                      q(3,8) * var(:,:,3) + q(4,8) * var(:,:,4) + &
+                      q(5,8) * var(:,:,5) + q(6,8) * var(:,:,6) + &
+                      q(7,8) * var(:,:,7) + q(9,8) * var(:,:,9) + &
+                      q(10,8) * var(:,:,10) + q(11,8) * var(:,:,11) + &
+                      q(12,8) * var(:,:,12) ) * idel
+      kl = 9
+    end if
+    if ( bb(2) == 0 ) then
+      kr = nk - gsize
+    else 
+      dvar(:,:,nk) =   - ( q(1,1) * var(:,:,nk) + q(2,1) * var(:,:,nk-1) + &
+                           q(3,1) * var(:,:,nk-2) + q(4,1) * var(:,:,nk-3) + &
+                           q(5,1) * var(:,:,nk-4) + q(6,1) * var(:,:,nk-5) + &
+                           q(7,1) * var(:,:,nk-6) + &
+                           q(8,1) * var(:,:,nk-7) ) * idel
+      dvar(:,:,nk-1) = - ( q(1,2) * var(:,:,nk) + q(3,2) * var(:,:,nk-2) + &
+                           q(4,2) * var(:,:,nk-3) + q(5,2) * var(:,:,nk-4) + &
+                           q(6,2) * var(:,:,nk-5) + q(7,2) * var(:,:,nk-6) + &
+                           q(8,2) * var(:,:,nk-7) ) * idel
+      dvar(:,:,nk-2) = - ( q(1,3) * var(:,:,nk) + q(2,3) * var(:,:,nk-1) + &
+                           q(4,3) * var(:,:,nk-3) + q(5,3) * var(:,:,nk-4) + &
+                           q(6,3) * var(:,:,nk-5) + q(7,3) * var(:,:,nk-6) + &
+                           q(8,3) * var(:,:,nk-7) ) * idel
+      dvar(:,:,nk-3) = - ( q(1,4) * var(:,:,nk) + q(2,4) * var(:,:,nk-1) + &
+                           q(3,4) * var(:,:,nk-2) + q(5,4) * var(:,:,nk-4) + &
+                           q(6,4) * var(:,:,nk-5) + q(7,4) * var(:,:,nk-6) + &
+                           q(8,4) * var(:,:,nk-7) ) * idel
+      dvar(:,:,nk-4) = - ( q(1,5) * var(:,:,nk) + q(2,5) * var(:,:,nk-1) + &
+                           q(3,5) * var(:,:,nk-2) + q(4,5) * var(:,:,nk-3) + &
+                           q(6,5) * var(:,:,nk-5) + q(7,5) * var(:,:,nk-6) + &
+                           q(8,5) * var(:,:,nk-7) + &
+                           q(9,5) * var(:,:,nk-8) ) * idel
+      dvar(:,:,nk-5) = - ( q(1,6) * var(:,:,nk) + q(2,6) * var(:,:,nk-1) + &
+                           q(3,6) * var(:,:,nk-2) + q(4,6) * var(:,:,nk-3) + &
+                           q(5,6) * var(:,:,nk-4) + q(7,6) * var(:,:,nk-6) + &
+                           q(8,6) * var(:,:,nk-7) + q(9,6) * var(:,:,nk-8) + &
+                           q(10,6) * var(:,:,nk-9) ) * idel
+      dvar(:,:,nk-6) = - ( q(1,7) * var(:,:,nk) + q(2,7) * var(:,:,nk-1) + &
+                           q(3,7) * var(:,:,nk-2) + q(4,7) * var(:,:,nk-3) + &
+                           q(5,7) * var(:,:,nk-4) + q(6,7) * var(:,:,nk-5) + &
+                           q(8,7) * var(:,:,nk-7) + q(9,7) * var(:,:,nk-8) + &
+                           q(10,7) * var(:,:,nk-9) + &
+                           q(11,7) * var(:,:,nk-10) ) * idel
+      dvar(:,:,nk-7) = - ( q(1,8) * var(:,:,nk) + q(2,8) * var(:,:,nk-1) + &
+                           q(3,8) * var(:,:,nk-2) + q(4,8) * var(:,:,nk-3) + &
+                           q(5,8) * var(:,:,nk-4) + q(6,8) * var(:,:,nk-5) + &
+                           q(7,8) * var(:,:,nk-6) + q(9,8) * var(:,:,nk-8) + &
+                           q(10,8) * var(:,:,nk-9) + &
+                           q(11,8) * var(:,:,nk-10) + &
+                           q(12,8) * var(:,:,nk-11) ) * idel
+      kr = nk - 8
+    end if
+    dvar(:,:,kl:kr) = ( a(1) * ( var(:,:,kl+1:kr+1) - &
+                                 var(:,:,kl-1:kr-1) ) + &
+                        a(2) * ( var(:,:,kl+2:kr+2) - &
+                                 var(:,:,kl-2:kr-2) ) + &
+                        a(3) * ( var(:,:,kl+3:kr+3) - &
+                                 var(:,:,kl-3:kr-3) ) + &
+                        a(4) * ( var(:,:,kl+4:kr+4) - &
+                                 var(:,:,kl-4:kr-4) ) ) * idel
+  end select direction
+end subroutine deriv_gf_8_4_opt
diff --git a/src/Dissipation_8_4.F90 b/src/Dissipation_8_4.F90
new file mode 100644
index 0000000..351541e
--- /dev/null
+++ b/src/Dissipation_8_4.F90
@@ -0,0 +1,467 @@
+! $Header$
+
+#include "cctk.h"
+
+subroutine dissipation_8_4 (var, ni, nj, nk, bb, gsize, delta, epsdis, rhs)
+
+  implicit none
+
+  integer ::  ni, nj, nk
+  CCTK_REAL, dimension(ni,nj,nk), intent(in) :: var
+  CCTK_REAL, dimension(ni,nj,nk), intent(inout) :: rhs
+  CCTK_INT, dimension(6), intent(in) :: bb
+  CCTK_INT, dimension(3), intent(in) :: gsize
+  CCTK_REAL, dimension(3), intent(in) :: delta
+  CCTK_REAL, intent(in) :: epsdis 
+
+  CCTK_REAL :: zero = 0.0
+  integer, parameter :: wp = kind(zero)
+  integer :: i, j, k
+  CCTK_REAL, dimension(12,8) :: a
+  CCTK_REAL :: idel
+
+  CCTK_INT :: il, ir, jl, jr, kl, kr
+
+  call set_coeff ( a )
+
+!  idel = epsdis / ( 256 * delta(1) )
+  idel = epsdis / 256
+
+  if ( bb(1) == 0 ) then
+    il = 1 + gsize(1)
+  else
+    rhs(1,:,:) = rhs(1,:,:) + &
+                 ( a(1,1) * var(1,:,:) + a(2,1) * var(2,:,:) + &
+                   a(3,1) * var(3,:,:) + a(4,1) * var(4,:,:) + &
+                   a(5,1) * var(5,:,:) ) * idel
+    rhs(2,:,:) = rhs(2,:,:) + &
+                 ( a(1,2) * var(1,:,:) + a(2,2) * var(2,:,:) + &
+                   a(3,2) * var(3,:,:) + a(4,2) * var(4,:,:) + &
+                   a(5,2) * var(5,:,:) + a(6,2) * var(6,:,:) ) * idel
+    rhs(3,:,:) = rhs(3,:,:) + &
+                 ( a(1,3) * var(1,:,:) + a(2,3) * var(2,:,:) + &
+                   a(3,3) * var(3,:,:) + a(4,3) * var(4,:,:) + &
+                   a(5,3) * var(5,:,:) + a(6,3) * var(6,:,:) + &
+                   a(7,3) * var(7,:,:) ) * idel
+    rhs(4,:,:) = rhs(4,:,:) + &
+                 ( a(1,4) * var(1,:,:) + a(2,4) * var(2,:,:) + &
+                   a(3,4) * var(3,:,:) + a(4,4) * var(4,:,:) + &
+                   a(5,4) * var(5,:,:) + a(6,4) * var(6,:,:) + &
+                   a(7,4) * var(7,:,:) + a(8,4) * var(8,:,:) ) * idel
+    rhs(5,:,:) = rhs(5,:,:) + &
+                 ( a(1,5) * var(1,:,:) + a(2,5) * var(2,:,:) + &
+                   a(3,5) * var(3,:,:) + a(4,5) * var(4,:,:) + &
+                   a(5,5) * var(5,:,:) + a(6,5) * var(6,:,:) + &
+                   a(7,5) * var(7,:,:) + a(8,5) * var(8,:,:) + &
+                   a(9,5) * var(9,:,:) ) * idel
+    rhs(6,:,:) = rhs(6,:,:) + &
+                 ( a(2,6) * var(2,:,:) + a(3,6) * var(3,:,:) + &
+                   a(4,6) * var(4,:,:) + a(5,6) * var(5,:,:) + &
+                   a(6,6) * var(6,:,:) + a(7,6) * var(7,:,:) + &
+                   a(8,6) * var(8,:,:) + a(9,6) * var(9,:,:) + &
+                   a(10,6) * var(10,:,:) ) * idel
+    rhs(7,:,:) = rhs(7,:,:) + &
+                 ( a(3,7) * var(3,:,:) + a(4,7) * var(4,:,:) + &
+                   a(5,7) * var(5,:,:) + a(6,7) * var(6,:,:) + &
+                   a(7,7) * var(7,:,:) + a(8,7) * var(8,:,:) + &
+                   a(9,7) * var(9,:,:) + a(10,7) * var(10,:,:) + &
+                   a(11,7) * var(11,:,:) ) * idel
+    rhs(8,:,:) = rhs(8,:,:) + &
+                 ( a(4,8) * var(4,:,:) + a(5,8) * var(5,:,:) + &
+                   a(6,8) * var(6,:,:) + a(7,8) * var(7,:,:) + &
+                   a(8,8) * var(8,:,:) + a(9,8) * var(9,:,:) + &
+                   a(10,8) * var(10,:,:) + a(11,8) * var(11,:,:) + &
+                   a(12,8) * var(12,:,:) ) * idel
+
+    il = 9
+  end if
+  if ( bb(2) == 0 ) then
+    ir = ni - gsize(1)
+  else
+    rhs(ni-7,:,:) = rhs(ni-7,:,:) + &
+                 ( a(4,8) * var(ni-3,:,:) + a(5,8) * var(ni-4,:,:) + &
+                   a(6,8) * var(ni-5,:,:) + a(7,8) * var(ni-6,:,:) + &
+                   a(8,8) * var(ni-7,:,:) + a(9,8) * var(ni-8,:,:) + &
+                   a(10,8) * var(ni-9,:,:) + a(11,8) * var(ni-10,:,:) + &
+                   a(12,8) * var(ni-11,:,:) ) * idel
+    rhs(ni-6,:,:) = rhs(ni-6,:,:) + &
+                 ( a(3,7) * var(ni-2,:,:) + a(4,7) * var(ni-3,:,:) + &
+                   a(5,7) * var(ni-4,:,:) + a(6,7) * var(ni-5,:,:) + &
+                   a(7,7) * var(ni-6,:,:) + a(8,7) * var(ni-7,:,:) + &
+                   a(9,7) * var(ni-8,:,:) + a(10,7) * var(ni-9,:,:) + &
+                   a(11,7) * var(ni-10,:,:) ) * idel
+    rhs(ni-5,:,:) = rhs(ni-5,:,:) + &
+                 ( a(2,6) * var(ni-1,:,:) + a(3,6) * var(ni-2,:,:) + &
+                   a(4,6) * var(ni-3,:,:) + a(5,6) * var(ni-4,:,:) + &
+                   a(6,6) * var(ni-5,:,:) + a(7,6) * var(ni-6,:,:) + &
+                   a(8,6) * var(ni-7,:,:) + a(9,6) * var(ni-8,:,:) + &
+                   a(10,6) * var(ni-9,:,:) ) * idel
+    rhs(ni-4,:,:) = rhs(ni-4,:,:) + &
+                 ( a(1,5) * var(ni,:,:) + a(2,5) * var(ni-1,:,:) + &
+                   a(3,5) * var(ni-2,:,:) + a(4,5) * var(ni-3,:,:) + &
+                   a(5,5) * var(ni-4,:,:) + a(6,5) * var(ni-5,:,:) + &
+                   a(7,5) * var(ni-6,:,:) + a(8,5) * var(ni-7,:,:) + &
+                   a(9,5) * var(ni-8,:,:) ) * idel
+    rhs(ni-3,:,:) = rhs(ni-3,:,:) + &
+                 ( a(1,4) * var(ni,:,:) + a(2,4) * var(ni-1,:,:) + &
+                   a(3,4) * var(ni-2,:,:) + a(4,4) * var(ni-3,:,:) + &
+                   a(5,4) * var(ni-4,:,:) + a(6,4) * var(ni-5,:,:) + &
+                   a(7,4) * var(ni-6,:,:) + a(8,4) * var(ni-7,:,:) ) * idel
+    rhs(ni-2,:,:) = rhs(ni-2,:,:) + &
+                 ( a(1,3) * var(ni,:,:) + a(2,3) * var(ni-1,:,:) + &
+                   a(3,3) * var(ni-2,:,:) + a(4,3) * var(ni-3,:,:) + &
+                   a(5,3) * var(ni-4,:,:) + a(6,3) * var(ni-5,:,:) + &
+                   a(7,3) * var(ni-6,:,:) ) * idel
+    rhs(ni-1,:,:) = rhs(ni-1,:,:) + &
+                 ( a(1,2) * var(ni,:,:) + a(2,2) * var(ni-1,:,:) + &
+                   a(3,2) * var(ni-2,:,:) + a(4,2) * var(ni-3,:,:) + &
+                   a(5,2) * var(ni-4,:,:) + a(6,2) * var(ni-5,:,:) ) * idel
+    rhs(ni,:,:)   = rhs(ni,:,:) + &
+                 ( a(1,1) * var(ni,:,:) + a(2,1) * var(ni-1,:,:) + &
+                   a(3,1) * var(ni-2,:,:) + a(4,1) * var(ni-3,:,:) + &
+                   a(5,1) * var(ni-4,:,:) ) * idel
+
+    ir = ni - 8
+  end if
+  rhs(il:ir,:,:) = rhs(il:ir,:,:) + &
+                   ( -70.0_wp * var(il:ir,:,:) + &
+                      56.0_wp * ( var(il-1:ir-1,:,:) + &
+                                  var(il+1:ir+1,:,:) ) - &
+                      28.0_wp * ( var(il-2:ir-2,:,:) + &
+                                  var(il+2:ir+2,:,:) ) + &
+                       8.0_wp * ( var(il-3:ir-3,:,:) + &
+                                  var(il+3:ir+3,:,:) ) - &
+                                ( var(il-4:ir-4,:,:) + &
+                                  var(il+4:ir+4,:,:) ) ) * idel
+
+  call set_coeff ( a )
+
+!  idel = epsdis / ( 256 * delta(2) )
+  idel = epsdis / 256
+
+  if ( bb(3) == 0 ) then
+    jl = 1 + gsize(2)
+  else
+    rhs(:,1,:) = rhs(:,1,:) + &
+                 ( a(1,1) * var(:,1,:) + a(2,1) * var(:,2,:) + &
+                   a(3,1) * var(:,3,:) + a(4,1) * var(:,4,:) + &
+                   a(5,1) * var(:,5,:) ) * idel
+    rhs(:,2,:) = rhs(:,2,:) + &
+                 ( a(1,2) * var(:,1,:) + a(2,2) * var(:,2,:) + &
+                   a(3,2) * var(:,3,:) + a(4,2) * var(:,4,:) + &
+                   a(5,2) * var(:,5,:) + a(6,2) * var(:,6,:) ) * idel
+    rhs(:,3,:) = rhs(:,3,:) + &
+                 ( a(1,3) * var(:,1,:) + a(2,3) * var(:,2,:) + &
+                   a(3,3) * var(:,3,:) + a(4,3) * var(:,4,:) + &
+                   a(5,3) * var(:,5,:) + a(6,3) * var(:,6,:) + &
+                   a(7,3) * var(:,7,:) ) * idel
+    rhs(:,4,:) = rhs(:,4,:) + &
+                 ( a(1,4) * var(:,1,:) + a(2,4) * var(:,2,:) + &
+                   a(3,4) * var(:,3,:) + a(4,4) * var(:,4,:) + &
+                   a(5,4) * var(:,5,:) + a(6,4) * var(:,6,:) + &
+                   a(7,4) * var(:,7,:) + a(8,4) * var(:,8,:) ) * idel
+    rhs(:,5,:) = rhs(:,5,:) + &
+                 ( a(1,5) * var(:,1,:) + a(2,5) * var(:,2,:) + &
+                   a(3,5) * var(:,3,:) + a(4,5) * var(:,4,:) + &
+                   a(5,5) * var(:,5,:) + a(6,5) * var(:,6,:) + &
+                   a(7,5) * var(:,7,:) + a(8,5) * var(:,8,:) + &
+                   a(9,5) * var(:,9,:) ) * idel
+    rhs(:,6,:) = rhs(:,6,:) + &
+                 ( a(2,6) * var(:,2,:) + a(3,6) * var(:,3,:) + &
+                   a(4,6) * var(:,4,:) + a(5,6) * var(:,5,:) + &
+                   a(6,6) * var(:,6,:) + a(7,6) * var(:,7,:) + &
+                   a(8,6) * var(:,8,:) + a(9,6) * var(:,9,:) + &
+                   a(10,6) * var(:,10,:) ) * idel
+    rhs(:,7,:) = rhs(:,7,:) + &
+                 ( a(3,7) * var(:,3,:) + a(4,7) * var(:,4,:) + &
+                   a(5,7) * var(:,5,:) + a(6,7) * var(:,6,:) + &
+                   a(7,7) * var(:,7,:) + a(8,7) * var(:,8,:) + &
+                   a(9,7) * var(:,9,:) + a(10,7) * var(:,10,:) + &
+                   a(11,7) * var(:,11,:) ) * idel
+    rhs(:,8,:) = rhs(:,8,:) + &
+                 ( a(4,8) * var(:,4,:) + a(5,8) * var(:,5,:) + &
+                   a(6,8) * var(:,6,:) + a(7,8) * var(:,7,:) + &
+                   a(8,8) * var(:,8,:) + a(9,8) * var(:,9,:) + &
+                   a(10,8) * var(:,10,:) + a(11,8) * var(:,11,:) + &
+                   a(12,8) * var(:,12,:) ) * idel
+
+    jl = 9
+  end if
+  if ( bb(4) == 0 ) then
+    jr = nj - gsize(2)
+  else
+    rhs(:,nj-7,:) = rhs(:,nj-7,:) + &
+                 ( a(4,8) * var(:,nj-3,:) + a(5,8) * var(:,nj-4,:) + &
+                   a(6,8) * var(:,nj-5,:) + a(7,8) * var(:,nj-6,:) + &
+                   a(8,8) * var(:,nj-7,:) + a(9,8) * var(:,nj-8,:) + &
+                   a(10,8) * var(:,nj-9,:) + a(11,8) * var(:,nj-10,:) + &
+                   a(12,8) * var(:,nj-11,:) ) * idel
+    rhs(:,nj-6,:) = rhs(:,nj-6,:) + &
+                 ( a(3,7) * var(:,nj-2,:) + a(4,7) * var(:,nj-3,:) + &
+                   a(5,7) * var(:,nj-4,:) + a(6,7) * var(:,nj-5,:) + &
+                   a(7,7) * var(:,nj-6,:) + a(8,7) * var(:,nj-7,:) + &
+                   a(9,7) * var(:,nj-8,:) + a(10,7) * var(:,nj-9,:) + &
+                   a(11,7) * var(:,nj-10,:) ) * idel
+    rhs(:,nj-5,:) = rhs(:,nj-5,:) + &
+                 ( a(2,6) * var(:,nj-1,:) + a(3,6) * var(:,nj-2,:) + &
+                   a(4,6) * var(:,nj-3,:) + a(5,6) * var(:,nj-4,:) + &
+                   a(6,6) * var(:,nj-5,:) + a(7,6) * var(:,nj-6,:) + &
+                   a(8,6) * var(:,nj-7,:) + a(9,6) * var(:,nj-8,:) + &
+                   a(10,6) * var(:,nj-9,:) ) * idel
+    rhs(:,nj-4,:) = rhs(:,nj-4,:) + &
+                 ( a(1,5) * var(:,nj,:) + a(2,5) * var(:,nj-1,:) + &
+                   a(3,5) * var(:,nj-2,:) + a(4,5) * var(:,nj-3,:) + &
+                   a(5,5) * var(:,nj-4,:) + a(6,5) * var(:,nj-5,:) + &
+                   a(7,5) * var(:,nj-6,:) + a(8,5) * var(:,nj-7,:) + &
+                   a(9,5) * var(:,nj-8,:) ) * idel
+    rhs(:,nj-3,:) = rhs(:,nj-3,:) + &
+                 ( a(1,4) * var(:,nj,:) + a(2,4) * var(:,nj-1,:) + &
+                   a(3,4) * var(:,nj-2,:) + a(4,4) * var(:,nj-3,:) + &
+                   a(5,4) * var(:,nj-4,:) + a(6,4) * var(:,nj-5,:) + &
+                   a(7,4) * var(:,nj-6,:) + a(8,4) * var(:,nj-7,:) ) * idel
+    rhs(:,nj-2,:) = rhs(:,nj-2,:) + &
+                 ( a(1,3) * var(:,nj,:) + a(2,3) * var(:,nj-1,:) + &
+                   a(3,3) * var(:,nj-2,:) + a(4,3) * var(:,nj-3,:) + &
+                   a(5,3) * var(:,nj-4,:) + a(6,3) * var(:,nj-5,:) + &
+                   a(7,3) * var(:,nj-6,:) ) * idel
+    rhs(:,nj-1,:) = rhs(:,nj-1,:) + &
+                 ( a(1,2) * var(:,nj,:) + a(2,2) * var(:,nj-1,:) + &
+                   a(3,2) * var(:,nj-2,:) + a(4,2) * var(:,nj-3,:) + &
+                   a(5,2) * var(:,nj-4,:) + a(6,2) * var(:,nj-5,:) ) * idel
+    rhs(:,nj,:)   = rhs(:,nj,:) + &
+                 ( a(1,1) * var(:,nj,:) + a(2,1) * var(:,nj-1,:) + &
+                   a(3,1) * var(:,nj-2,:) + a(4,1) * var(:,nj-3,:) + &
+                   a(5,1) * var(:,nj-4,:) ) * idel
+
+    jr = nj - 8
+  end if
+  rhs(:,jl:jr,:) = rhs(:,jl:jr,:) + &
+                   ( -70.0_wp * var(:,jl:jr,:) + &
+                      56.0_wp * ( var(:,jl-1:jr-1,:) + &
+                                  var(:,jl+1:jr+1,:) ) - &
+                      28.0_wp * ( var(:,jl-2:jr-2,:) + &
+                                  var(:,jl+2:jr+2,:) ) + &
+                       8.0_wp * ( var(:,jl-3:jr-3,:) + &
+                                  var(:,jl+3:jr+3,:) ) - &
+                                ( var(:,jl-4:jr-4,:) + &
+                                  var(:,jl+4:jr+4,:) ) ) * idel
+
+  call set_coeff ( a )
+
+!  idel = epsdis / ( 256 * delta(3) )
+  idel = epsdis / 256
+
+  if ( bb(5) == 0 ) then
+    kl = 1 + gsize(3)
+  else
+    rhs(:,:,1) = rhs(:,:,1) + &
+                 ( a(1,1) * var(:,:,1) + a(2,1) * var(:,:,2) + &
+                   a(3,1) * var(:,:,3) + a(4,1) * var(:,:,4) + &
+                   a(5,1) * var(:,:,5) ) * idel
+    rhs(:,:,2) = rhs(:,:,2) + &
+                 ( a(1,2) * var(:,:,1) + a(2,2) * var(:,:,2) + &
+                   a(3,2) * var(:,:,3) + a(4,2) * var(:,:,4) + &
+                   a(5,2) * var(:,:,5) + a(6,2) * var(:,:,6) ) * idel
+    rhs(:,:,3) = rhs(:,:,3) + &
+                 ( a(1,3) * var(:,:,1) + a(2,3) * var(:,:,2) + &
+                   a(3,3) * var(:,:,3) + a(4,3) * var(:,:,4) + &
+                   a(5,3) * var(:,:,5) + a(6,3) * var(:,:,6) + &
+                   a(7,3) * var(:,:,7) ) * idel
+    rhs(:,:,4) = rhs(:,:,4) + &
+                 ( a(1,4) * var(:,:,1) + a(2,4) * var(:,:,2) + &
+                   a(3,4) * var(:,:,3) + a(4,4) * var(:,:,4) + &
+                   a(5,4) * var(:,:,5) + a(6,4) * var(:,:,6) + &
+                   a(7,4) * var(:,:,7) + a(8,4) * var(:,:,8) ) * idel
+    rhs(:,:,5) = rhs(:,:,5) + &
+                 ( a(1,5) * var(:,:,1) + a(2,5) * var(:,:,2) + &
+                   a(3,5) * var(:,:,3) + a(4,5) * var(:,:,4) + &
+                   a(5,5) * var(:,:,5) + a(6,5) * var(:,:,6) + &
+                   a(7,5) * var(:,:,7) + a(8,5) * var(:,:,8) + &
+                   a(9,5) * var(:,:,9) ) * idel
+    rhs(:,:,6) = rhs(:,:,6) + &
+                 ( a(2,6) * var(:,:,2) + a(3,6) * var(:,:,3) + &
+                   a(4,6) * var(:,:,4) + a(5,6) * var(:,:,5) + &
+                   a(6,6) * var(:,:,6) + a(7,6) * var(:,:,7) + &
+                   a(8,6) * var(:,:,8) + a(9,6) * var(:,:,9) + &
+                   a(10,6) * var(:,:,10) ) * idel
+    rhs(:,:,7) = rhs(:,:,7) + &
+                 ( a(3,7) * var(:,:,3) + a(4,7) * var(:,:,4) + &
+                   a(5,7) * var(:,:,5) + a(6,7) * var(:,:,6) + &
+                   a(7,7) * var(:,:,7) + a(8,7) * var(:,:,8) + &
+                   a(9,7) * var(:,:,9) + a(10,7) * var(:,:,10) + &
+                   a(11,7) * var(:,:,11) ) * idel
+    rhs(:,:,8) = rhs(:,:,8) + &
+                 ( a(4,8) * var(:,:,4) + a(5,8) * var(:,:,5) + &
+                   a(6,8) * var(:,:,6) + a(7,8) * var(:,:,7) + &
+                   a(8,8) * var(:,:,8) + a(9,8) * var(:,:,9) + &
+                   a(10,8) * var(:,:,10) + a(11,8) * var(:,:,11) + &
+                   a(12,8) * var(:,:,12) ) * idel
+
+    kl = 9
+  end if
+  if ( bb(6) == 0 ) then
+    kr = nk - gsize(3)
+  else
+    rhs(:,:,nk-7) = rhs(:,:,nk-7) + &
+                 ( a(4,8) * var(:,:,nk-3) + a(5,8) * var(:,:,nk-4) + &
+                   a(6,8) * var(:,:,nk-5) + a(7,8) * var(:,:,nk-6) + &
+                   a(8,8) * var(:,:,nk-7) + a(9,8) * var(:,:,nk-8) + &
+                   a(10,8) * var(:,:,nk-9) + a(11,8) * var(:,:,nk-10) + &
+                   a(12,8) * var(:,:,nk-11) ) * idel
+    rhs(:,:,nk-6) = rhs(:,:,nk-6) + &
+                 ( a(3,7) * var(:,:,nk-2) + a(4,7) * var(:,:,nk-3) + &
+                   a(5,7) * var(:,:,nk-4) + a(6,7) * var(:,:,nk-5) + &
+                   a(7,7) * var(:,:,nk-6) + a(8,7) * var(:,:,nk-7) + &
+                   a(9,7) * var(:,:,nk-8) + a(10,7) * var(:,:,nk-9) + &
+                   a(11,7) * var(:,:,nk-10) ) * idel
+    rhs(:,:,nk-5) = rhs(:,:,nk-5) + &
+                 ( a(2,6) * var(:,:,nk-1) + a(3,6) * var(:,:,nk-2) + &
+                   a(4,6) * var(:,:,nk-3) + a(5,6) * var(:,:,nk-4) + &
+                   a(6,6) * var(:,:,nk-5) + a(7,6) * var(:,:,nk-6) + &
+                   a(8,6) * var(:,:,nk-7) + a(9,6) * var(:,:,nk-8) + &
+                   a(10,6) * var(:,:,nk-9) ) * idel
+    rhs(:,:,nk-4) = rhs(:,:,nk-4) + &
+                 ( a(1,5) * var(:,:,nk) + a(2,5) * var(:,:,nk-1) + &
+                   a(3,5) * var(:,:,nk-2) + a(4,5) * var(:,:,nk-3) + &
+                   a(5,5) * var(:,:,nk-4) + a(6,5) * var(:,:,nk-5) + &
+                   a(7,5) * var(:,:,nk-6) + a(8,5) * var(:,:,nk-7) + &
+                   a(9,5) * var(:,:,nk-8) ) * idel
+    rhs(:,:,nk-3) = rhs(:,:,nk-3) + &
+                 ( a(1,4) * var(:,:,nk) + a(2,4) * var(:,:,nk-1) + &
+                   a(3,4) * var(:,:,nk-2) + a(4,4) * var(:,:,nk-3) + &
+                   a(5,4) * var(:,:,nk-4) + a(6,4) * var(:,:,nk-5) + &
+                   a(7,4) * var(:,:,nk-6) + a(8,4) * var(:,:,nk-7) ) * idel
+    rhs(:,:,nk-2) = rhs(:,:,nk-2) + &
+                 ( a(1,3) * var(:,:,nk) + a(2,3) * var(:,:,nk-1) + &
+                   a(3,3) * var(:,:,nk-2) + a(4,3) * var(:,:,nk-3) + &
+                   a(5,3) * var(:,:,nk-4) + a(6,3) * var(:,:,nk-5) + &
+                   a(7,3) * var(:,:,nk-6) ) * idel
+    rhs(:,:,nk-1) = rhs(:,:,nk-1) + &
+                 ( a(1,2) * var(:,:,nk) + a(2,2) * var(:,:,nk-1) + &
+                   a(3,2) * var(:,:,nk-2) + a(4,2) * var(:,:,nk-3) + &
+                   a(5,2) * var(:,:,nk-4) + a(6,2) * var(:,:,nk-5) ) * idel
+    rhs(:,:,nk)   = rhs(:,:,nk) + &
+                 ( a(1,1) * var(:,:,nk) + a(2,1) * var(:,:,nk-1) + &
+                   a(3,1) * var(:,:,nk-2) + a(4,1) * var(:,:,nk-3) + &
+                   a(5,1) * var(:,:,nk-4) ) * idel
+    kr = nk - 8
+  end if
+  rhs(:,:,kl:kr) = rhs(:,:,kl:kr) + &
+                   ( -70.0_wp * var(:,:,kl:kr) + &
+                      56.0_wp * ( var(:,:,kl-1:kr-1) + &
+                                  var(:,:,kl+1:kr+1) ) - &
+                      28.0_wp * ( var(:,:,kl-2:kr-2) + &
+                                  var(:,:,kl+2:kr+2) ) + &
+                       8.0_wp * ( var(:,:,kl-3:kr-3) + &
+                                  var(:,:,kl+3:kr+3) ) - &
+                                ( var(:,:,kl-4:kr-4) + &
+                                  var(:,:,kl+4:kr+4) ) ) * idel
+contains
+
+  subroutine set_coeff ( a )
+
+    implicit none
+
+    CCTK_REAL, dimension(12,8), intent(OUT) :: a
+    CCTK_REAL :: zero = 0.0
+    integer, parameter :: wp = kind(zero)
+
+    a(1,1) = -3.3910872088637970174997113084967416241083103770745_wp
+    a(2,1) = 13.564348835455188069998845233986966496433241508298_wp
+    a(3,1) = -20.346523253182782104998267850980449744649862262447_wp
+    a(4,1) = 13.564348835455188069998845233986966496433241508298_wp
+    a(5,1) = -3.3910872088637970174997113084967416241083103770745_wp
+    a(6,1) = 0.0_wp
+    a(7,1) = 0.0_wp
+    a(8,1) = 0.0_wp
+    a(9,1) = 0.0_wp
+    a(10,1) = 0.0_wp
+    a(11,1) = 0.0_wp
+    a(12,1) = 0.0_wp
+    a(1,2) = 2.6217119552210904473646423259312909608627056453179_wp
+    a(2,2) = -11.142275809689634401299729885207986583666498992601_wp
+    a(3,2) = 18.351983686547633131552496281519036726038939517225_wp
+    a(4,2) = -14.419415753715997460505532792622100284744881049248_wp
+    a(5,2) = 5.2434239104421808947292846518625819217254112906357_wp
+    a(6,2) = -0.65542798880527261184116058148282274021567641132947_wp
+    a(7,2) = 0.0_wp
+    a(8,2) = 0.0_wp
+    a(9,2) = 0.0_wp
+    a(10,2) = 0.0_wp
+    a(11,2) = 0.0_wp
+    a(12,2) = 0.0_wp
+    a(1,3) = -23.305235778623380376667790568855064784933288377246_wp
+    a(2,3) = 108.75776696690910842444968932132363566302201242715_wp
+    a(3,3) = -205.86291604450652666056548335821973893357738066567_wp
+    a(4,3) = 201.97871008140262993112085159674389480275516593613_wp
+    a(5,3) = -108.75776696690910842444968932132363566302201242715_wp
+    a(6,3) = 31.073647704831173835557054091806753046577717836328_wp
+    a(7,3) = -3.8842059631038967294446317614758441308222147295410_wp
+    a(8,3) = 0.0_wp
+    a(9,3) = 0.0_wp
+    a(10,3) = 0.0_wp
+    a(11,3) = 0.0_wp
+    a(12,3) = 0.0_wp
+    a(1,4) = 2.2245534287765737751523181243817045070532621097794_wp
+    a(2,4) = -12.235043858271155763337749684099374788792941603787_wp
+    a(3,4) = 28.919194574095459076980135616962158591692407427132_wp
+    a(4,4) = -38.373546646395897621377487645584402746668771393695_wp
+    a(5,4) = 31.143748002872032852132453741343863098745669536912_wp
+    a(6,4) = -15.571874001436016426066226870671931549372834768456_wp
+    a(7,4) = 4.4491068575531475503046362487634090141065242195588_wp
+    a(8,4) = -0.55613835719414344378807953109542612676331552744485_wp
+    a(9,4) = 0.0_wp
+    a(10,4) = 0.0_wp
+    a(11,4) = 0.0_wp
+    a(12,4) = 0.0_wp
+    a(1,5) = -2.4230202953323072711308162536265511957185829658094_wp
+    a(2,5) = 19.384162362658458169046530029012409565748663726475_wp
+    a(3,5) = -67.844568269304603591662855101543433480120323042664_wp
+    a(4,5) = 135.68913653860920718332571020308686696024064608533_wp
+    a(5,5) = -169.61142067326150897915713775385858370030080760666_wp
+    a(6,5) = 135.68913653860920718332571020308686696024064608533_wp
+    a(7,5) = -67.844568269304603591662855101543433480120323042664_wp
+    a(8,5) = 19.384162362658458169046530029012409565748663726475_wp
+    a(9,5) = -2.4230202953323072711308162536265511957185829658094_wp
+    a(10,5) = 0.0_wp
+    a(11,5) = 0.0_wp
+    a(12,5) = 0.0_wp
+    a(1,6) = 0.0_wp
+    a(2,6) = -0.78217600900123184961735065035840034142603567514089_wp
+    a(3,6) = 6.2574080720098547969388052028672027314082854011271_wp
+    a(4,6) = -21.900928252034491789285818210035209559928998903945_wp
+    a(5,6) = 43.801856504068983578571636420070419119857997807890_wp
+    a(6,6) = -54.752320630086229473214545525088023899822497259862_wp
+    a(7,6) = 43.801856504068983578571636420070419119857997807890_wp
+    a(8,6) = -21.900928252034491789285818210035209559928998903945_wp
+    a(9,6) = 6.2574080720098547969388052028672027314082854011271_wp
+    a(10,6) = -0.78217600900123184961735065035840034142603567514089_wp
+    a(11,6) = 0.0_wp
+    a(12,6) = 0.0_wp
+    a(1,7) = 0.0_wp
+    a(2,7) = 0.0_wp
+    a(3,7) = -1.0830767761393601764536458481012280421614377748694_wp
+    a(4,7) = 8.6646142091148814116291667848098243372915021989551_wp
+    a(5,7) = -30.326149731902084940702083746834385180520257696343_wp
+    a(6,7) = 60.652299463804169881404167493668770361040515392685_wp
+    a(7,7) = -75.815374329755212351755209367085962951300644240857_wp
+    a(8,7) = 60.652299463804169881404167493668770361040515392685_wp
+    a(9,7) = -30.326149731902084940702083746834385180520257696343_wp
+    a(10,7) = 8.6646142091148814116291667848098243372915021989551_wp
+    a(11,7) = -1.0830767761393601764536458481012280421614377748694_wp
+    a(12,7) = 0.0_wp
+    a(1,8) = 0.0_wp
+    a(2,8) = 0.0_wp
+    a(3,8) = 0.0_wp
+    a(4,8) = -0.99075245444434671889501396229410272246695863420506_wp
+    a(5,8) = 7.9260196355547737511601116983528217797356690736404_wp
+    a(6,8) = -27.741068724441708129060390944234876229074841757742_wp
+    a(7,8) = 55.482137448883416258120781888469752458149683515483_wp
+    a(8,8) = -69.352671811104270322650977360587190572687104394354_wp
+    a(9,8) = 55.482137448883416258120781888469752458149683515483_wp
+    a(10,8) = -27.741068724441708129060390944234876229074841757742_wp
+    a(11,8) = 7.9260196355547737511601116983528217797356690736404_wp
+    a(12,8) = -0.99075245444434671889501396229410272246695863420506_wp
+
+  end subroutine set_coeff
+end subroutine dissipation_8_4
diff --git a/src/call_derivs.c b/src/call_derivs.c
index 2932e24..7d69c6d 100644
--- a/src/call_derivs.c
+++ b/src/call_derivs.c
@@ -45,6 +45,15 @@ void DiffGv ( const CCTK_POINTER_TO_CONST cctkGH_, const CCTK_INT dir,
                                        const CCTK_INT *gsize,
                                        const CCTK_REAL *delta,
                                        CCTK_REAL *dvar);
+  void CCTK_FCALL CCTK_FNAME(deriv_gf_4_3_opt)(const CCTK_REAL *var,
+                                       const CCTK_INT *ni,
+                                       const CCTK_INT *nj,
+                                       const CCTK_INT *nk,
+                                       const CCTK_INT *dir,
+                                       const CCTK_INT *bb,
+                                       const CCTK_INT *gsize,
+                                       const CCTK_REAL *delta,
+                                       CCTK_REAL *dvar);
   void CCTK_FCALL CCTK_FNAME(deriv_gf_6_3)(const CCTK_REAL *var,
                                        const CCTK_INT *ni,
                                        const CCTK_INT *nj,
@@ -63,6 +72,15 @@ void DiffGv ( const CCTK_POINTER_TO_CONST cctkGH_, const CCTK_INT dir,
                                        const CCTK_INT *gsize,
                                        const CCTK_REAL *delta,
                                        CCTK_REAL *dvar);
+  void CCTK_FCALL CCTK_FNAME(deriv_gf_6_5_opt)(const CCTK_REAL *var,
+                                       const CCTK_INT *ni,
+                                       const CCTK_INT *nj,
+                                       const CCTK_INT *nk,
+                                       const CCTK_INT *dir,
+                                       const CCTK_INT *bb,
+                                       const CCTK_INT *gsize,
+                                       const CCTK_REAL *delta,
+                                       CCTK_REAL *dvar);
   void CCTK_FCALL CCTK_FNAME(deriv_gf_8_4)(const CCTK_REAL *var,
                                        const CCTK_INT *ni,
                                        const CCTK_INT *nj,
@@ -72,6 +90,15 @@ void DiffGv ( const CCTK_POINTER_TO_CONST cctkGH_, const CCTK_INT dir,
                                        const CCTK_INT *gsize,
                                        const CCTK_REAL *delta,
                                        CCTK_REAL *dvar);
+  void CCTK_FCALL CCTK_FNAME(deriv_gf_8_4_opt)(const CCTK_REAL *var,
+                                       const CCTK_INT *ni,
+                                       const CCTK_INT *nj,
+                                       const CCTK_INT *nk,
+                                       const CCTK_INT *dir,
+                                       const CCTK_INT *bb,
+                                       const CCTK_INT *gsize,
+                                       const CCTK_REAL *delta,
+                                       CCTK_REAL *dvar);
 
   
   ni = cctk_lsh[0]; nj = cctk_lsh[1]; nk = cctk_lsh[2];
@@ -111,38 +138,64 @@ void DiffGv ( const CCTK_POINTER_TO_CONST cctkGH_, const CCTK_INT dir,
   }
 
   if ( CCTK_Equals(norm_type,"Diagonal") ) {
-    switch(loc_order) {
-    case 2: {
-      CCTK_FNAME(deriv_gf_2_1)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
-      break;
-    }
-    case 4: {
-      CCTK_FNAME(deriv_gf_4_2)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
-      break;
-    }
-    case 6: {
-      CCTK_FNAME(deriv_gf_6_3)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
-      break;
-    }
-    case 8: {
-      CCTK_FNAME(deriv_gf_8_4)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
-      break;
-    }
-    default:
-      CCTK_WARN (0, "Unknown stencil specified");
+    if ( CCTK_Equals(operator_type,"Minimal Bandwidth") ) {
+      switch(loc_order) {
+      case 2: {
+        CCTK_FNAME(deriv_gf_2_1)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      case 4: {
+        CCTK_FNAME(deriv_gf_4_2)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      case 6: {
+        CCTK_FNAME(deriv_gf_6_3)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      case 8: {
+        CCTK_FNAME(deriv_gf_8_4)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      default:
+        CCTK_WARN (0, "Unknown stencil specified");
+      }
+    } else {
+      switch(loc_order) {
+      case 8: {
+        CCTK_FNAME(deriv_gf_8_4_opt)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      default:
+        CCTK_WARN (0, "Unknown stencil specified");
+      }
     }
   } else {
-    switch(loc_order) {
-    case 4: {
-      CCTK_FNAME(deriv_gf_4_3)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
-      break;
-    }
-    case 6: {
-      CCTK_FNAME(deriv_gf_6_5)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
-      break;
-    }
-    default:
-      CCTK_WARN (0, "Unknown stencil specified");
+    if ( CCTK_Equals(operator_type,"Minimal Bandwidth") ) {
+      switch(loc_order) {
+      case 4: {
+        CCTK_FNAME(deriv_gf_4_3)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      case 6: {
+        CCTK_FNAME(deriv_gf_6_5)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      default:
+        CCTK_WARN (0, "Unknown stencil specified");
+      }
+    } else {
+      switch(loc_order) {
+      case 4: {
+        CCTK_FNAME(deriv_gf_4_3_opt)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      case 6: {
+        CCTK_FNAME(deriv_gf_6_5_opt)(var,&ni,&nj,&nk,&dir,bb,&gsize,&delta,dvar);
+        break;
+      }
+      default:
+        CCTK_WARN (0, "Unknown stencil specified");
+      }
     }
   }
 } 
diff --git a/src/dissipation.c b/src/dissipation.c
index 50d99a8..638a47a 100644
--- a/src/dissipation.c
+++ b/src/dissipation.c
@@ -16,6 +16,15 @@ void CCTK_FCALL CCTK_FNAME(dissipation_6_5) (const CCTK_REAL *var,
                                              const CCTK_REAL *dx,
                                              const CCTK_REAL *epsdis,
                                              CCTK_REAL *rhs);
+void CCTK_FCALL CCTK_FNAME(dissipation_8_4) (const CCTK_REAL *var,
+                                             const CCTK_INT *ni,
+                                             const CCTK_INT *nj,
+                                             const CCTK_INT *nk,
+                                             const CCTK_INT *bbox,
+                                             const CCTK_INT *gsize,
+                                             const CCTK_REAL *dx,
+                                             const CCTK_REAL *epsdis,
+                                             CCTK_REAL *rhs);
 
 static void
 apply (int const varindex, char const * const optstring, void * const arg);
@@ -103,7 +112,16 @@ apply (int const varindex, char const * const optstring, void * const arg)
   assert (rhsptr);
   
   if ( CCTK_Equals(norm_type,"Diagonal") ) {
-    assert(0);
+    switch(order) {
+    case 8: {
+      CCTK_FNAME(dissipation_8_4)
+        (varptr, &cctk_lsh[0], &cctk_lsh[1], &cctk_lsh[2],
+                            bbox, gsize, dx, &epsdis, rhsptr);
+      break;
+    }
+    default:
+      assert(0);
+    }
   } else {
     switch(order) {
     case 6: {
diff --git a/src/make.code.defn b/src/make.code.defn
index 882479e..040c89d 100644
--- a/src/make.code.defn
+++ b/src/make.code.defn
@@ -8,6 +8,7 @@ SRCS =  call_derivs.c \
         Derivatives_4_2.F90 \
         Derivatives_6_3.F90 \
         Derivatives_8_4.F90 \
+        Derivatives_8_4_min_err_coeff.F90 \
         Derivatives_4_3.F90 \
         Derivatives_4_3_min_err_coeff.F90 \
         Derivatives_6_5.F90 \
@@ -16,6 +17,7 @@ SRCS =  call_derivs.c \
         set_norm_mask.F90 \
         CheckGridSizes.F90 \
         dissipation.c \
+        Dissipation_8_4.F90 \
         Dissipation_6_5.F90 \
         get_coeffs.c \
         Coefficients_2_1.F90 \
@@ -24,6 +26,7 @@ SRCS =  call_derivs.c \
         Coefficients_8_4.F90 \
         Coefficients_4_3.F90 \
         Coefficients_6_5.F90
+#        Derivatives_8_4_opt5.F90 \
 
 # Subdirectories containing source files
 SUBDIRS =