C $Header: /u/gcmpack/MITgcm/pkg/generic_advdiff/gad_ppm_p3e_r.F,v 1.1 2016/03/13 01:44:03 jmc Exp $ C $Name: $ # include "GAD_OPTIONS.h" SUBROUTINE GAD_PPM_P3E_R(bi,bj,ix,iy, & mask,fbar,edge,myThid) C |================================================================| C | PPM_P3E_R: approximate edge values with degree-3 polynomials. | C | Fixed grid-spacing variant in R. | C |================================================================| implicit none C =============================================== global variables # include "SIZE.h" # include "GRID.h" # include "GAD.h" C ====================================================== arguments integer bi,bj,ix,iy _RL mask(1-3:Nr+3) _RL fbar(1-3:Nr+3) _RL edge(1-0:Nr+1) integer myThid C ====================================================== variables integer ir _RL mloc(-2:+1) _RL floc(-2:+1) _RL ftmp do ir = +1, Nr+1 C ================ mask local stencil: expand from centre outwards mloc(-1) = mask(ir-1) mloc(+0) = mask(ir+0) floc(-1) = fbar(ir+0) & + mloc(-1)*(fbar(ir-1)-fbar(ir+0)) floc(+0) = fbar(ir-1) & + mloc(+0)*(fbar(ir+0)-fbar(ir-1)) mloc(-2) = mask(ir-2) * mloc(-1) ftmp = 2. _d 0 * floc(-1) - floc(+0) floc(-2) = ftmp & + mloc(-2)*(fbar(ir-2)-ftmp) mloc(+1) = mask(ir+1) * mloc(+0) ftmp = 2. _d 0 * floc(+0) - floc(-1) floc(+1) = ftmp & + mloc(+1)*(fbar(ir+1)-ftmp) C ================ centred, 3rd-order interpolation for edge value edge(ir) = & -(1. _d 0 / 12. _d 0)*(floc(-2)+floc(+1)) & +(7. _d 0 / 12. _d 0)*(floc(-1)+floc(+0)) end
do return c end subroutine GAD_PPM_P3E_R end