pkg/exf/exf_interp.F

#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_in, 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       = 1,11,21 for bilinear; 2,12,22 for bicubic
C                    1,2 for tracer; 11,12 for U; 21,22 for V
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_in      (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
      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 lagran
      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)
      real*8   ninety      PARAMETER ( ninety = 90. )
      integer  i, j, k, l, js, bi, bj, sp, interp_unit
      _RS      xG(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
      _RS      threeSixtyRS, NorthValue
      PARAMETER ( threeSixtyRS = 360. )

C     put xG in interval [ lon_0 , lon_0+360 [
      do bj=myByLo(myThid),myByHi(myThid)
       do bi=myBxLo(myThid),myBxHi(myThid)
        do j=1-OLy,sNy+OLy
         do i=1-OLx,sNx+OLx
          xG(i,j,bi,bj) = xG_in(i,j,bi,bj)-lon_0
     &                  + threeSixtyRS*2.
          xG(i,j,bi,bj) = lon_0+mod(xG(i,j,bi,bj),threeSixtyRS)
         enddo
        enddo
       enddo
      enddo

       call exf_interp_read(
     I   infile, filePrec,
     O   arrayin,
     I   irecord, nx_in, ny_in, mythid)
      _BARRIER

C     _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
c       y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
c       y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
       y_in(ny_in+1) = min( y_in(ny_in) + lat_inc(ny_in-1), ninety )
       y_in(ny_in+2) = min( y_in(ny_in) + 2.*lat_inc(ny_in-1), ninety )

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

C     For tracer (method=1,2) set to northernmost zonal-mean value
C     at 90N to avoid sharp zonal gradients near the Pole.
C     For U (method=11,12) set to zero at 90N to minimize velocity
C     gradient at North Pole
C     For V (method=11,12) set to northernmost zonal value at 90N,
C     as is already done above in order to allow cross-PoleArctic flow
       if (y_in(ny_in+1).eq.ninety) then
        if (method.eq.1 .or. method.eq.2) then
         NorthValue = 0
         do i=1,nx_in
          NorthValue = NorthValue + arrayin(i,ny_in)
         enddo
         NorthValue = NorthValue / nx_in
         do i=-1,nx_in+2
          arrayin(i,ny_in+1) = NorthValue
         enddo
        elseif (method.eq.11 .or. method.eq.12) then
         do i=-1,nx_in+2
          arrayin(i,ny_in+1) = 0
         enddo
        endif
       endif
       if (y_in(ny_in+2).eq.ninety) then
        if (method.eq.1 .or. method.eq.2) then
         NorthValue = 0
         do i=1,nx_in
          NorthValue = NorthValue + arrayin(i,ny_in)
         enddo
         NorthValue = NorthValue / nx_in
         do i=-1,nx_in+2
          arrayin(i,ny_in+2) = NorthValue
         enddo
        elseif (method.eq.11 .or. method.eq.12) then
         do i=-1,nx_in+2
          arrayin(i,ny_in+2) = 0
         enddo
        endif
       endif

C     _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 .or. method.eq.11 .or. method.eq.21) 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 .or. method.eq.12 .or. method.eq.22) 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
1	edhill	1.3	#include "EXF_OPTIONS.h"
2	dimitri	1.1	CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
3			C Flux Coupler using C
4			C Bilinear interpolation of forcing fields C
5			C C
6			C B. Cheng (12/2002) C
7			C C
8			C added Bicubic (bnc 1/2003) C
9			C C
10			CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
11
12	dimitri	1.2	real*8 function lagran(i,x,a,sp)
13	dimitri	1.1
14			INTEGER i,k,sp
15			_RS x
16			real*8 a(4)
17			real*8 numer,denom
18
19			numer = 1.D0
20			denom = 1.D0
21
22			do k=1,sp
23			if ( k .ne. i) then
24			denom = denom*(a(i) - a(k))
25			numer = numer*(x - a(k))
26			endif
27			enddo
28
29			lagran = numer/denom
30
31			return
32			end
33
34
35			SUBROUTINE exf_interp(
36			I infile,
37			I filePrec,
38			O arrayout,
39	heimbach	1.13	I irecord, xG_in, yG,
40	dimitri	1.2	I lon_0, lon_inc,
41			I lat_0, lat_inc,
42			I nx_in, ny_in, method, mythid)
43	dimitri	1.1
44	dimitri	1.4	implicit none
45
46	dimitri	1.2	C infile = name of the input file (direct access binary)
47			C filePrec = file precicision (currently not used, assumes real*4)
48	dimitri	1.1	C arrout = output arrays (different for each processor)
49			C irecord = record number in global file
50			C xG,yG = coordinates for output grid
51			C lon_0, lat_0 = lon and lat of sw corner of global input grid
52			C lon_inc = scalar x-grid increment
53			C lat_inc = vector y-grid increments
54			C nx_in, ny_in = input x-grid and y-grid size
55	dimitri	1.15	C method = 1,11,21 for bilinear; 2,12,22 for bicubic
56			C 1,2 for tracer; 11,12 for U; 21,22 for V
57	dimitri	1.2	C mythid = thread id
58	dimitri	1.1	C
59
60			#include "SIZE.h"
61			#include "EEPARAMS.h"
62	adcroft	1.7	#include "PARAMS.h"
63	dimitri	1.2
64			C subroutine variables
65			character() infile
66			integer filePrec, irecord, nx_in, ny_in
67			_RL arrayout(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
68	heimbach	1.12	_RS xG_in (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
69	dimitri	1.2	_RS yG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
70			_RL lon_0, lon_inc
71			_RL lat_0, lat_inc(ny_in-1)
72			integer method, mythid
73	dimitri	1.1
74			C local variables
75	dimitri	1.5	integer e_ind(snx,sny),w_ind(snx,sny)
76			integer n_ind(snx,sny),s_ind(snx,sny)
77	dimitri	1.2	real*8 px_ind(4), py_ind(4), ew_val(4)
78	dimitri	1.1	external lagran
79	dimitri	1.2	real*8 lagran
80			real*4 arrayin(-1:nx_in+2 , -1:ny_in+2)
81			real*8 x_in (-1:nx_in+2), y_in(-1:ny_in+2)
82	dimitri	1.16	real*8 ninety PARAMETER ( ninety = 90. )
83	dimitri	1.5	integer i, j, k, l, js, bi, bj, sp, interp_unit
84	heimbach	1.13	_RS xG(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
85	dimitri	1.15	_RS threeSixtyRS, NorthValue
86	heimbach	1.13	PARAMETER ( threeSixtyRS = 360. )
87	heimbach	1.12
88	jmc	1.14	C put xG in interval [ lon_0 , lon_0+360 [
89	heimbach	1.12	do bj=myByLo(myThid),myByHi(myThid)
90			do bi=myBxLo(myThid),myBxHi(myThid)
91			do j=1-OLy,sNy+OLy
92			do i=1-OLx,sNx+OLx
93	jmc	1.14	xG(i,j,bi,bj) = xG_in(i,j,bi,bj)-lon_0
94			& + threeSixtyRS*2.
95			xG(i,j,bi,bj) = lon_0+mod(xG(i,j,bi,bj),threeSixtyRS)
96	heimbach	1.12	enddo
97			enddo
98			enddo
99			enddo
100	heimbach	1.9
101			call exf_interp_read(
102	dimitri	1.15	I infile, filePrec,
103	heimbach	1.9	O arrayin,
104	dimitri	1.15	I irecord, nx_in, ny_in, mythid)
105	cnh	1.11	_BARRIER
106	dimitri	1.4
107	cnh	1.11	C _BEGIN_MASTER( myThid )
108	dimitri	1.2
109	dimitri	1.1	C setup input grid
110	dimitri	1.4	do i=-1,nx_in+2
111	jmc	1.14	x_in(i) = lon_0 + (i-1)*lon_inc
112	dimitri	1.4	enddo
113	heimbach	1.12
114	dimitri	1.4	y_in(0) = lat_0 - lat_inc(1)
115			y_in(-1)= lat_0 - 2.*lat_inc(1)
116			y_in(1) = lat_0
117			do j=2,ny_in
118			y_in(j) = y_in(j-1) + lat_inc(j-1)
119			enddo
120	dimitri	1.15	c y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
121			c y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
122	dimitri	1.16	y_in(ny_in+1) = min( y_in(ny_in) + lat_inc(ny_in-1), ninety )
123			y_in(ny_in+2) = min( y_in(ny_in) + 2.*lat_inc(ny_in-1), ninety )
124	dimitri	1.1
125			C enlarge boundary
126	dimitri	1.4	do j=1,ny_in
127			arrayin(0,j) = arrayin(nx_in,j)
128			arrayin(-1,j) = arrayin(nx_in-1,j)
129			arrayin(nx_in+1,j) = arrayin(1,j)
130			arrayin(nx_in+2,j) = arrayin(2,j)
131			enddo
132			do i=-1,nx_in+2
133			arrayin(i,0) = arrayin(i,1)
134			arrayin(i,-1) = arrayin(i,1)
135			arrayin(i,ny_in+1) = arrayin(i,ny_in)
136			arrayin(i,ny_in+2) = arrayin(i,ny_in)
137			enddo
138
139	dimitri	1.15	C For tracer (method=1,2) set to northernmost zonal-mean value
140			C at 90N to avoid sharp zonal gradients near the Pole.
141			C For U (method=11,12) set to zero at 90N to minimize velocity
142			C gradient at North Pole
143			C For V (method=11,12) set to northernmost zonal value at 90N,
144			C as is already done above in order to allow cross-PoleArctic flow
145	dimitri	1.16	if (y_in(ny_in+1).eq.ninety) then
146	dimitri	1.15	if (method.eq.1 .or. method.eq.2) then
147			NorthValue = 0
148			do i=1,nx_in
149			NorthValue = NorthValue + arrayin(i,ny_in)
150			enddo
151			NorthValue = NorthValue / nx_in
152			do i=-1,nx_in+2
153			arrayin(i,ny_in+1) = NorthValue
154			enddo
155			elseif (method.eq.11 .or. method.eq.12) then
156			do i=-1,nx_in+2
157			arrayin(i,ny_in+1) = 0
158			enddo
159			endif
160			endif
161	dimitri	1.16	if (y_in(ny_in+2).eq.ninety) then
162	dimitri	1.15	if (method.eq.1 .or. method.eq.2) then
163			NorthValue = 0
164			do i=1,nx_in
165			NorthValue = NorthValue + arrayin(i,ny_in)
166			enddo
167			NorthValue = NorthValue / nx_in
168			do i=-1,nx_in+2
169			arrayin(i,ny_in+2) = NorthValue
170			enddo
171			elseif (method.eq.11 .or. method.eq.12) then
172			do i=-1,nx_in+2
173			arrayin(i,ny_in+2) = 0
174			enddo
175			endif
176			endif
177
178	cnh	1.11	C _END_MASTER( myThid )
179	dimitri	1.15
180	dimitri	1.2	do bj = mybylo(mythid), mybyhi(mythid)
181			do bi = mybxlo(mythid), mybxhi(mythid)
182
183			C check validity of input/output coordinates
184	dimitri	1.6	#ifdef ALLOW_DEBUG
185			if ( debugLevel .ge. debLevB ) then
186			do i=1,snx
187			do j=1,sny
188			if ( xG(i,j,bi,bj) .lt. x_in(0) .or.
189			& xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or.
190			& yG(i,j,bi,bj) .lt. y_in(0) .or.
191			& yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then
192			print*,'ERROR in S/R EXF_INTERP:'
193			print*,' input grid must encompass output grid.'
194			print*,'i,j,bi,bj' ,i,j,bi,bj
195			print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj)
196			print*,'nx_in,ny_in' ,nx_in ,ny_in
197			print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1)
198			print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1)
199			STOP ' ABNORMAL END: S/R EXF_INTERP'
200			endif
201			enddo
202			enddo
203	dimitri	1.2	endif
204	dimitri	1.6	#endif /* ALLOW_DEBUG */
205	dimitri	1.1
206			C compute interpolation indices
207			do i=1,snx
208	dimitri	1.5	do j=1,sny
209			if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then
210			w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1
211			else
212			w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc)
213			endif
214			e_ind(i,j) = w_ind(i,j) + 1
215	dimitri	1.6	js = ny_in*.5
216	dimitri	1.5	do while (yG(i,j,bi,bj) .lt. y_in(js))
217	dimitri	1.6	js = (js - 1)*.5
218	dimitri	1.5	enddo
219			do while (yG(i,j,bi,bj) .ge. y_in(js+1))
220			js = js + 1
221			enddo
222			s_ind(i,j) = js
223			n_ind(i,j) = js + 1
224	dimitri	1.2	enddo
225	dimitri	1.1	enddo
226
227	dimitri	1.15	if (method.eq.1 .or. method.eq.11 .or. method.eq.21) then
228	dimitri	1.1
229	dimitri	1.2	C bilinear interpolation
230			sp = 2
231			do j=1,sny
232			do i=1,snx
233	dimitri	1.1	arrayout(i,j,bi,bj) = 0.
234	dimitri	1.2	do l=0,1
235	dimitri	1.5	px_ind(l+1) = x_in(w_ind(i,j)+l)
236			py_ind(l+1) = y_in(s_ind(i,j)+l)
237	dimitri	1.1	enddo
238	dimitri	1.2	do k=1,2
239	dimitri	1.5	ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1)
240			& *lagran(1,xG(i,j,bi,bj),px_ind,sp)
241			& +arrayin(e_ind(i,j),s_ind(i,j)+k-1)
242			& *lagran(2,xG(i,j,bi,bj),px_ind,sp)
243	dimitri	1.2	arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
244	dimitri	1.5	& +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
245	dimitri	1.1	enddo
246			enddo
247			enddo
248	dimitri	1.15	elseif (method .eq. 2 .or. method.eq.12 .or. method.eq.22) then
249	dimitri	1.1
250	dimitri	1.2	C bicubic interpolation
251			sp = 4
252			do j=1,sny
253			do i=1,snx
254	dimitri	1.1	arrayout(i,j,bi,bj) = 0.
255	dimitri	1.2	do l=-1,2
256	dimitri	1.5	px_ind(l+2) = x_in(w_ind(i,j)+l)
257			py_ind(l+2) = y_in(s_ind(i,j)+l)
258	dimitri	1.1	enddo
259	dimitri	1.2	do k=1,4
260			ew_val(k) =
261	dimitri	1.5	& arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2)
262			& *lagran(1,xG(i,j,bi,bj),px_ind,sp)
263			& +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2)
264			& *lagran(2,xG(i,j,bi,bj),px_ind,sp)
265			& +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2)
266			& *lagran(3,xG(i,j,bi,bj),px_ind,sp)
267			& +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2)
268			& *lagran(4,xG(i,j,bi,bj),px_ind,sp)
269	dimitri	1.2	arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
270	dimitri	1.5	& +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
271	dimitri	1.1	enddo
272	dimitri	1.2	enddo
273	dimitri	1.1	enddo
274	dimitri	1.2	else
275			stop 'stop in exf_interp.F: interpolation method not supported'
276			endif
277			enddo
278			enddo
279	dimitri	1.1
280			END