/[MITgcm]/MITgcm/pkg/exf/exf_interp.F
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Contents of /MITgcm/pkg/exf/exf_interp.F

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Revision 1.9 - (show annotations) (download)
Sat Apr 30 16:20:40 2005 UTC (19 years, 1 month ago) by heimbach
Branch: MAIN
Changes since 1.8: +9 -52 lines
We would like to use exf_interp also for adjoint,
so move I/O part to separate routine and hide it.

1 #include "EXF_OPTIONS.h"
2 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 real*8 function lagran(i,x,a,sp)
13
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 I irecord, xG, yG,
40 I lon_0, lon_inc,
41 I lat_0, lat_inc,
42 I nx_in, ny_in, method, mythid)
43
44 implicit none
45
46 C infile = name of the input file (direct access binary)
47 C filePrec = file precicision (currently not used, assumes real*4)
48 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 C method = 1 for bilinear 2 for bicubic
56 C mythid = thread id
57 C
58
59 #include "SIZE.h"
60 #include "EEPARAMS.h"
61 #ifdef ALLOW_USE_MPI
62 # include "EESUPPORT.h"
63 #endif /* ALLOW_USE_MPI */
64 #include "PARAMS.h"
65
66 C subroutine variables
67 character*(*) infile
68 integer filePrec, irecord, nx_in, ny_in
69 _RL arrayout(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
70 _RS xG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
71 _RS yG (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
72 _RL lon_0, lon_inc
73 _RL lat_0, lat_inc(ny_in-1)
74 integer method, mythid
75
76 C local variables
77 real*8 ne_fac,nw_fac,se_fac,sw_fac
78 integer e_ind(snx,sny),w_ind(snx,sny)
79 integer n_ind(snx,sny),s_ind(snx,sny)
80 real*8 px_ind(4), py_ind(4), ew_val(4)
81 external lagran
82 real*8 lagran
83 real*4 arrayin(-1:nx_in+2 , -1:ny_in+2)
84 real*8 x_in (-1:nx_in+2), y_in(-1:ny_in+2)
85 integer i, j, k, l, js, bi, bj, sp, interp_unit
86
87 call exf_interp_read(
88 I infile,
89 I filePrec,
90 O arrayin,
91 I irecord, xG, yG,
92 I lon_0, lon_inc,
93 I lat_0, lat_inc,
94 I nx_in, ny_in, method, mythid)
95
96 _BEGIN_MASTER( myThid )
97
98 C setup input grid
99 do i=-1,nx_in+2
100 x_in(i) = lon_0 + (i-1.)*lon_inc
101 enddo
102 y_in(0) = lat_0 - lat_inc(1)
103 y_in(-1)= lat_0 - 2.*lat_inc(1)
104 y_in(1) = lat_0
105 do j=2,ny_in
106 y_in(j) = y_in(j-1) + lat_inc(j-1)
107 enddo
108 y_in(ny_in+1) = y_in(ny_in) + lat_inc(ny_in-1)
109 y_in(ny_in+2) = y_in(ny_in) + 2.*lat_inc(ny_in-1)
110
111 C enlarge boundary
112 do j=1,ny_in
113 arrayin(0,j) = arrayin(nx_in,j)
114 arrayin(-1,j) = arrayin(nx_in-1,j)
115 arrayin(nx_in+1,j) = arrayin(1,j)
116 arrayin(nx_in+2,j) = arrayin(2,j)
117 enddo
118 do i=-1,nx_in+2
119 arrayin(i,0) = arrayin(i,1)
120 arrayin(i,-1) = arrayin(i,1)
121 arrayin(i,ny_in+1) = arrayin(i,ny_in)
122 arrayin(i,ny_in+2) = arrayin(i,ny_in)
123 enddo
124
125 _END_MASTER( myThid )
126
127 do bj = mybylo(mythid), mybyhi(mythid)
128 do bi = mybxlo(mythid), mybxhi(mythid)
129
130 C check validity of input/output coordinates
131 #ifdef ALLOW_DEBUG
132 if ( debugLevel .ge. debLevB ) then
133 do i=1,snx
134 do j=1,sny
135 if ( xG(i,j,bi,bj) .lt. x_in(0) .or.
136 & xG(i,j,bi,bj) .ge. x_in(nx_in+1) .or.
137 & yG(i,j,bi,bj) .lt. y_in(0) .or.
138 & yG(i,j,bi,bj) .ge. y_in(ny_in+1) ) then
139 print*,'ERROR in S/R EXF_INTERP:'
140 print*,' input grid must encompass output grid.'
141 print*,'i,j,bi,bj' ,i,j,bi,bj
142 print*,'xG,yG' ,xG(i,j,bi,bj),yG(i,j,bi,bj)
143 print*,'nx_in,ny_in' ,nx_in ,ny_in
144 print*,'x_in(0,nx_in+1)',x_in(0) ,x_in(nx_in+1)
145 print*,'y_in(0,ny_in+1)',y_in(0) ,y_in(ny_in+1)
146 STOP ' ABNORMAL END: S/R EXF_INTERP'
147 endif
148 enddo
149 enddo
150 endif
151 #endif /* ALLOW_DEBUG */
152
153 C compute interpolation indices
154 do i=1,snx
155 do j=1,sny
156 if (xG(i,j,bi,bj)-x_in(1) .ge. 0.) then
157 w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc) + 1
158 else
159 w_ind(i,j) = int((xG(i,j,bi,bj)-x_in(1))/lon_inc)
160 endif
161 e_ind(i,j) = w_ind(i,j) + 1
162 js = ny_in*.5
163 do while (yG(i,j,bi,bj) .lt. y_in(js))
164 js = (js - 1)*.5
165 enddo
166 do while (yG(i,j,bi,bj) .ge. y_in(js+1))
167 js = js + 1
168 enddo
169 s_ind(i,j) = js
170 n_ind(i,j) = js + 1
171 enddo
172 enddo
173
174 if (method .eq. 1) then
175
176 C bilinear interpolation
177 sp = 2
178 do j=1,sny
179 do i=1,snx
180 arrayout(i,j,bi,bj) = 0.
181 do l=0,1
182 px_ind(l+1) = x_in(w_ind(i,j)+l)
183 py_ind(l+1) = y_in(s_ind(i,j)+l)
184 enddo
185 do k=1,2
186 ew_val(k) = arrayin(w_ind(i,j),s_ind(i,j)+k-1)
187 & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
188 & +arrayin(e_ind(i,j),s_ind(i,j)+k-1)
189 & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
190 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
191 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
192 enddo
193 enddo
194 enddo
195 elseif (method .eq. 2) then
196
197 C bicubic interpolation
198 sp = 4
199 do j=1,sny
200 do i=1,snx
201 arrayout(i,j,bi,bj) = 0.
202 do l=-1,2
203 px_ind(l+2) = x_in(w_ind(i,j)+l)
204 py_ind(l+2) = y_in(s_ind(i,j)+l)
205 enddo
206 do k=1,4
207 ew_val(k) =
208 & arrayin(w_ind(i,j)-1,s_ind(i,j)+k-2)
209 & *lagran(1,xG(i,j,bi,bj),px_ind,sp)
210 & +arrayin(w_ind(i,j) ,s_ind(i,j)+k-2)
211 & *lagran(2,xG(i,j,bi,bj),px_ind,sp)
212 & +arrayin(e_ind(i,j) ,s_ind(i,j)+k-2)
213 & *lagran(3,xG(i,j,bi,bj),px_ind,sp)
214 & +arrayin(e_ind(i,j)+1,s_ind(i,j)+k-2)
215 & *lagran(4,xG(i,j,bi,bj),px_ind,sp)
216 arrayout(i,j,bi,bj)=arrayout(i,j,bi,bj)
217 & +ew_val(k)*lagran(k,yG(i,j,bi,bj),py_ind,sp)
218 enddo
219 enddo
220 enddo
221 else
222 stop 'stop in exf_interp.F: interpolation method not supported'
223 endif
224 enddo
225 enddo
226
227 END

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