#include "EXF_OPTIONS.h"
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
C Flux Coupler using C
C Bilinear interpolation of forcing fields C
C C
C B. Cheng (12/2002) C
C C
C added Bicubic (bnc 1/2003) C
C C
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
real*8 function lagran(i,x,a,sp)
INTEGER i,k,sp
_RS x
real*8 a(4)
real*8 numer,denom
numer = 1.D0
denom = 1.D0
do k=1,sp
if ( k .ne. i) then
denom = denom*(a(i) - a(k))
numer = numer*(x - a(k))
endif
enddo
lagran = numer/denom
return
end
SUBROUTINE EXF_INTERP(
I infile,
I filePrec,
O arrayout,
I irecord, xG, yG,
I lon_0, lon_inc,
I lat_0, lat_inc,
I nx_in, ny_in, method, mythid)
implicit none
C infile = name of the input file (direct access binary)
C filePrec = file precicision (currently not used, assumes real*4)
C arrout = output arrays (different for each processor)
C irecord = record number in global file
C xG,yG = coordinates for output grid
C lon_0, lat_0 = lon and lat of sw corner of global input grid
C lon_inc = scalar x-grid increment
C lat_inc = vector y-grid increments
C nx_in, ny_in = input x-grid and y-grid size
C method = 1 for bilinear 2 for bicubic
C mythid = thread id
C
#include "SIZE.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
C subroutine variables
character*(*) infile
integer filePrec, irecord, nx_in, ny_in
_RL arrayout(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
_RS xG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
_RS yG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
_RL lon_0, lon_inc
_RL lat_0, lat_inc(ny_in-1)
integer method, mythid
C local variables
real*8 ne_fac,nw_fac,se_fac,sw_fac
integer e_ind(snx,sny),w_ind(snx,sny)
integer n_ind(snx,sny),s_ind(snx,sny)
real*8 px_ind(4), py_ind(4), ew_val(4)
external
real*8 lagran
real*4 arrayin(-1:nx_in+2 , -1:ny_in+2)
real*8 x_in (-1:nx_in+2), y_in(-1:ny_in+2)
integer i, j, k, l, js, bi, bj, sp, interp_unit
call EXF_INTERP_READ(
I infile,
I filePrec,
O arrayin,
I irecord, xG, yG,
I lon_0, lon_inc,
I lat_0, lat_inc,
I nx_in, ny_in, method, mythid)
_BEGIN_MASTER( myThid )
C setup input grid
do i=-1,nx_in+2
x_in(i) = lon_0 + (i-1.)*lon_inc
enddo
y_in(0) = lat_0 - lat_inc(1)
y_in(-1)= lat_0 - 2.*lat_inc(1)
y_in(1) = lat_0
do j=2,ny_in
y_in(j) = y_in(j-1) + lat_inc(j-1)
enddo
y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
C enlarge boundary
do j=1,ny_in
arrayin(0,j) = arrayin(nx_in,j)
arrayin(-1,j) = arrayin(nx_in-1,j)
arrayin(nx_in+1,j) = arrayin(1,j)
arrayin(nx_in+2,j) = arrayin(2,j)
enddo
do i=-1,nx_in+2
arrayin(i,0) = arrayin(i,1)
arrayin(i,-1) = arrayin(i,1)
arrayin(i,ny_in+1) = arrayin(i,ny_in)
arrayin(i,ny_in+2) = arrayin(i,ny_in)
enddo
_END_MASTER( myThid )
do bj = mybylo(mythid), mybyhi(mythid)
do bi = mybxlo(mythid), mybxhi(mythid)
C check validity of input/output coordinates
#ifdef ALLOW_DEBUG
if ( debugLevel .ge. debLevB ) then
do i=1,snx
do j=1,sny
if ( xG(i,j,bi,bj) .lt. x_in(0) .or.
& xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or.
& yG(i,j,bi,bj) .lt. y_in(0) .or.
& yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then
print*,'ERROR in S/R EXF_INTERP:'
print*,' input grid must encompass output grid.'
print*,'i,j,bi,bj' ,i,j,bi,bj
print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj)
print*,'nx_in,ny_in' ,nx_in ,ny_in
print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1)
print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1)
STOP ' ABNORMAL END: S/R EXF_INTERP'
endif
enddo
enddo
endif
#endif /* ALLOW_DEBUG */
C compute interpolation indices
do i=1,snx
do j=1,sny
if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then
w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1
else
w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc)
endif
e_ind(i,j) = w_ind(i,j) + 1
js = ny_in*.5
do while (yG(i,j,bi,bj) .lt. y_in(js))
js = (js - 1)*.5
enddo
do while (yG(i,j,bi,bj) .ge. y_in(js+1))
js = js + 1
enddo
s_ind(i,j) = js
n_ind(i,j) = js + 1
enddo
enddo
if (method .eq. 1) then
C bilinear interpolation
sp = 2
do j=1,sny
do i=1,snx
arrayout(i,j,bi,bj) = 0.
do l=0,1
px_ind(l+1) = x_in(w_ind(i,j)+l)
py_ind(l+1) = y_in(s_ind(i,j)+l)
enddo
do k=1,2
ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1)
& *lagran(1,xG(i,j,bi,bj),px_ind,sp)
& +arrayin(e_ind(i,j),s_ind(i,j)+k-1)
& *lagran(2,xG(i,j,bi,bj),px_ind,sp)
arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
& +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
enddo
enddo
enddo
elseif (method .eq. 2) then
C bicubic interpolation
sp = 4
do j=1,sny
do i=1,snx
arrayout(i,j,bi,bj) = 0.
do l=-1,2
px_ind(l+2) = x_in(w_ind(i,j)+l)
py_ind(l+2) = y_in(s_ind(i,j)+l)
enddo
do k=1,4
ew_val(k) =
& arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2)
& *lagran(1,xG(i,j,bi,bj),px_ind,sp)
& +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2)
& *lagran(2,xG(i,j,bi,bj),px_ind,sp)
& +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2)
& *lagran(3,xG(i,j,bi,bj),px_ind,sp)
& +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2)
& *lagran(4,xG(i,j,bi,bj),px_ind,sp)
arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
& +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
enddo
enddo
enddo
else
stop 'stop in exf_interp.F: interpolation method not supported'
endif
enddo
enddo
END