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Revision 1.21 - (hide annotations) (download)
Thu Apr 4 07:02:51 2013 UTC (12 years, 3 months ago) by mlosch
Branch: MAIN
Changes since 1.20: +3 -5 lines
simplify the use of CPP flags (compile when SEAICE_ALLOW_JFNK is defined)

1 mlosch 1.21 C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_jfnk.F,v 1.20 2013/03/02 04:35:05 jmc Exp $
2 mlosch 1.1 C $Name: $
3    
4     #include "SEAICE_OPTIONS.h"
5    
6 mlosch 1.15 C-- File seaice_jfnk.F: seaice jfnk dynamical solver S/R:
7     C-- Contents
8     C-- o SEAICE_JFNK
9     C-- o SEAICE_JFNK_UPDATE
10    
11 mlosch 1.1 CBOP
12     C !ROUTINE: SEAICE_JFNK
13     C !INTERFACE:
14     SUBROUTINE SEAICE_JFNK( myTime, myIter, myThid )
15    
16     C !DESCRIPTION: \bv
17     C *==========================================================*
18 mlosch 1.15 C | SUBROUTINE SEAICE_JFNK
19 mlosch 1.1 C | o Ice dynamics using a Jacobian-free Newton-Krylov solver
20     C | following J.-F. Lemieux et al. Improving the numerical
21     C | convergence of viscous-plastic sea ice models with the
22     C | Jacobian-free Newton-Krylov method. J. Comp. Phys. 229,
23     C | 2840-2852 (2010).
24     C | o The logic follows JFs code.
25     C *==========================================================*
26     C | written by Martin Losch, Oct 2012
27     C *==========================================================*
28     C \ev
29    
30     C !USES:
31     IMPLICIT NONE
32    
33     C === Global variables ===
34     #include "SIZE.h"
35     #include "EEPARAMS.h"
36     #include "PARAMS.h"
37     #include "DYNVARS.h"
38     #include "GRID.h"
39     #include "SEAICE_SIZE.h"
40     #include "SEAICE_PARAMS.h"
41     #include "SEAICE.h"
42    
43     #ifdef ALLOW_AUTODIFF_TAMC
44     # include "tamc.h"
45     #endif
46    
47     C !INPUT/OUTPUT PARAMETERS:
48     C === Routine arguments ===
49     C myTime :: Simulation time
50     C myIter :: Simulation timestep number
51     C myThid :: my Thread Id. number
52     _RL myTime
53     INTEGER myIter
54     INTEGER myThid
55    
56 mlosch 1.21 #ifdef SEAICE_ALLOW_JFNK
57 mlosch 1.5 C !FUNCTIONS:
58     LOGICAL DIFFERENT_MULTIPLE
59     EXTERNAL DIFFERENT_MULTIPLE
60 mlosch 1.1
61 mlosch 1.16 C !LOCAL VARIABLES:
62     C === Local variables ===
63 mlosch 1.1 C i,j,bi,bj :: loop indices
64     INTEGER i,j,bi,bj
65     C loop indices
66 mlosch 1.5 INTEGER newtonIter
67     INTEGER krylovIter, krylovFails
68 mlosch 1.13 INTEGER totalKrylovItersLoc, totalNewtonItersLoc
69 mlosch 1.5 C FGMRES flag that determines amount of output messages of fgmres
70     INTEGER iOutFGMRES
71     C FGMRES flag that indicates what fgmres wants us to do next
72 mlosch 1.1 INTEGER iCode
73 mlosch 1.13 _RL JFNKresidual
74 mlosch 1.1 _RL JFNKresidualKm1
75     C parameters to compute convergence criterion
76     _RL phi_e, alp_e, JFNKgamma_lin
77     _RL FGMRESeps
78     _RL JFNKtol
79 jmc 1.20
80 mlosch 1.1 _RL recip_deltaT
81     LOGICAL JFNKconverged, krylovConverged
82 mlosch 1.9 LOGICAL writeNow
83 mlosch 1.1 CHARACTER*(MAX_LEN_MBUF) msgBuf
84 jmc 1.20
85 mlosch 1.1 C u/vIceRes :: residual of sea-ice momentum equations
86     _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
87     _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
88     C du/vIce :: ice velocity increment to be added to u/vIce
89     _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
90     _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
91 jmc 1.20 C precomputed (= constant per Newton iteration) versions of
92 mlosch 1.2 C zeta, eta, and DWATN, press
93     _RL zetaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
94     _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
95 mlosch 1.8 _RL etaZPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
96 mlosch 1.2 _RL dwatPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
97 mlosch 1.1 CEOP
98    
99     C Initialise
100 mlosch 1.5 newtonIter = 0
101     krylovFails = 0
102     totalKrylovItersLoc = 0
103     JFNKconverged = .FALSE.
104     JFNKtol = 0. _d 0
105     JFNKresidual = 0. _d 0
106     JFNKresidualKm1 = 0. _d 0
107     FGMRESeps = 0. _d 0
108     recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
109    
110     iOutFGMRES=0
111 mlosch 1.12 C with iOutFgmres=1, seaice_fgmres prints the residual at each iteration
112     IF ( debugLevel.GE.debLevC .AND.
113 mlosch 1.5 & DIFFERENT_MULTIPLE( SEAICE_monFreq, myTime, deltaTClock ) )
114     & iOutFGMRES=1
115    
116 mlosch 1.1 DO bj=myByLo(myThid),myByHi(myThid)
117     DO bi=myBxLo(myThid),myBxHi(myThid)
118 jmc 1.20 DO J=1-OLy,sNy+OLy
119     DO I=1-OLx,sNx+OLx
120 mlosch 1.1 uIceRes(I,J,bi,bj) = 0. _d 0
121     vIceRes(I,J,bi,bj) = 0. _d 0
122     duIce (I,J,bi,bj) = 0. _d 0
123     dvIce (I,J,bi,bj) = 0. _d 0
124     uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
125     vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
126     ENDDO
127     ENDDO
128     C Compute things that do no change during the Newton iteration:
129 jmc 1.20 C sea-surface tilt and wind stress:
130 mlosch 1.1 C FORCEX/Y0 - mass*(u/vIceNm1)/deltaT
131 jmc 1.20 DO J=1-OLy,sNy+OLy
132     DO I=1-OLx,sNx+OLx
133 mlosch 1.1 FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
134 jmc 1.20 & + seaiceMassU(I,J,bi,bj)*uIceNm1(I,J,bi,bj)*recip_deltaT
135 mlosch 1.1 FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
136 jmc 1.20 & + seaiceMassV(I,J,bi,bj)*vIceNm1(I,J,bi,bj)*recip_deltaT
137 mlosch 1.1 ENDDO
138     ENDDO
139     ENDDO
140     ENDDO
141     C Start nonlinear Newton iteration: outer loop iteration
142     DO WHILE ( newtonIter.LT.SEAICEnewtonIterMax .AND.
143     & .NOT.JFNKconverged )
144     newtonIter = newtonIter + 1
145     C Compute initial residual F(u), (includes computation of global
146     C variables DWATN, zeta, and eta)
147 jmc 1.20 IF ( newtonIter .EQ. 1 ) CALL SEAICE_JFNK_UPDATE(
148     I duIce, dvIce,
149 mlosch 1.15 U uIce, vIce, JFNKresidual,
150     O uIceRes, vIceRes,
151     I newtonIter, myTime, myIter, myThid )
152 mlosch 1.1 C local copies of precomputed coefficients that are to stay
153     C constant for the preconditioner
154     DO bj=myByLo(myThid),myByHi(myThid)
155     DO bi=myBxLo(myThid),myBxHi(myThid)
156 jmc 1.20 DO j=1-OLy,sNy+OLy
157     DO i=1-OLx,sNx+OLx
158 mlosch 1.10 zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
159     etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
160     etaZPre(I,J,bi,bj) = etaZ(I,J,bi,bj)
161     dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
162 mlosch 1.1 ENDDO
163     ENDDO
164     ENDDO
165     ENDDO
166     C compute convergence criterion for linear preconditioned FGMRES
167     JFNKgamma_lin = JFNKgamma_lin_max
168 mlosch 1.18 IF ( newtonIter.GT.1.AND.newtonIter.LE.SEAICE_JFNK_tolIter
169 mlosch 1.1 & .AND.JFNKresidual.LT.JFNKres_t ) THEN
170 jmc 1.20 C Eisenstat, 1996, equ.(2.6)
171 mlosch 1.1 phi_e = 1. _d 0
172     alp_e = 1. _d 0
173     JFNKgamma_lin = phi_e*( JFNKresidual/JFNKresidualKm1 )**alp_e
174     JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
175     JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
176     ENDIF
177     C save the residual for the next iteration
178     JFNKresidualKm1 = JFNKresidual
179 jmc 1.20
180 mlosch 1.1 C The Krylov iteration using FGMRES, the preconditioner is LSOR
181     C for now. The code is adapted from SEAICE_LSR, but heavily stripped
182     C down.
183     C krylovIter is mapped into "its" in seaice_fgmres and is incremented
184     C in that routine
185     krylovIter = 0
186     iCode = 0
187 jmc 1.20
188 mlosch 1.1 JFNKconverged = JFNKresidual.LT.JFNKtol
189 jmc 1.20
190 mlosch 1.1 C do Krylov loop only if convergence is not reached
191 jmc 1.20
192 mlosch 1.1 IF ( .NOT.JFNKconverged ) THEN
193 jmc 1.20
194 mlosch 1.1 C start Krylov iteration (FGMRES)
195 jmc 1.20
196 mlosch 1.1 krylovConverged = .FALSE.
197     FGMRESeps = JFNKgamma_lin * JFNKresidual
198 jmc 1.20 DO WHILE ( .NOT.krylovConverged )
199 mlosch 1.1 C solution vector sol = du/vIce
200     C residual vector (rhs) Fu = u/vIceRes
201 jmc 1.20 C output work vectors wk1, -> input work vector wk2
202    
203 mlosch 1.1 CALL SEAICE_FGMRES_DRIVER(
204 jmc 1.20 I uIceRes, vIceRes,
205 mlosch 1.1 U duIce, dvIce, iCode,
206 mlosch 1.5 I FGMRESeps, iOutFGMRES,
207 mlosch 1.1 I newtonIter, krylovIter, myTime, myIter, myThid )
208     C FGMRES returns iCode either asking for an new preconditioned vector
209     C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
210     C iteration
211     IF (iCode.EQ.1) THEN
212 jmc 1.20 C Call preconditioner
213 mlosch 1.7 IF ( SOLV_MAX_ITERS .GT. 0 )
214 jmc 1.20 & CALL SEAICE_PRECONDITIONER(
215     U duIce, dvIce,
216     I zetaPre, etaPre, etaZpre, dwatPre,
217 mlosch 1.1 I newtonIter, krylovIter, myTime, myIter, myThid )
218     ELSEIF (iCode.GE.2) THEN
219     C Compute Jacobian times vector
220     CALL SEAICE_JACVEC(
221     I uIce, vIce, uIceRes, vIceRes,
222 jmc 1.20 U duIce, dvIce,
223 mlosch 1.1 I newtonIter, krylovIter, myTime, myIter, myThid )
224     ENDIF
225     krylovConverged = iCode.EQ.0
226     C End of Krylov iterate
227     ENDDO
228 mlosch 1.5 totalKrylovItersLoc = totalKrylovItersLoc + krylovIter
229 mlosch 1.1 C some output diagnostics
230     IF ( debugLevel.GE.debLevA ) THEN
231 mlosch 1.5 _BEGIN_MASTER( myThid )
232 jmc 1.20 totalNewtonItersLoc =
233 mlosch 1.13 & SEAICEnewtonIterMax*(myIter-nIter0)+newtonIter
234 jmc 1.20 WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
235 mlosch 1.13 & ' S/R SEAICE_JFNK: Newton iterate / total, ',
236     & 'JFNKgamma_lin, initial norm = ',
237     & newtonIter, totalNewtonItersLoc,
238     & JFNKgamma_lin,JFNKresidual
239     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
240     & SQUEEZE_RIGHT, myThid )
241 mlosch 1.1 WRITE(msgBuf,'(3(A,I6))')
242 jmc 1.20 & ' S/R SEAICE_JFNK: Newton iterate / total = ',newtonIter,
243 mlosch 1.13 & ' / ', totalNewtonItersLoc,
244 mlosch 1.1 & ', Nb. of FGMRES iterations = ', krylovIter
245     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
246     & SQUEEZE_RIGHT, myThid )
247 mlosch 1.5 _END_MASTER( myThid )
248 mlosch 1.1 ENDIF
249     IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN
250 mlosch 1.5 krylovFails = krylovFails + 1
251 mlosch 1.1 ENDIF
252 mlosch 1.17 C Set the stopping criterion for the Newton iteration and the
253     C criterion for the transition from accurate to approximate FGMRES
254     IF ( newtonIter .EQ. 1 ) THEN
255     JFNKtol=JFNKgamma_nonlin*JFNKresidual
256     IF ( JFNKres_tFac .NE. UNSET_RL )
257     & JFNKres_t = JFNKresidual * JFNKres_tFac
258     ENDIF
259 mlosch 1.1 C Update linear solution vector and return to Newton iteration
260 mlosch 1.15 C Do a linesearch if necessary, and compute a new residual.
261     C Note that it should be possible to do the following operations
262     C at the beginning of the Newton iteration, thereby saving us from
263     C the extra call of seaice_jfnk_update, but unfortunately that
264     C changes the results, so we leave the stuff here for now.
265 jmc 1.20 CALL SEAICE_JFNK_UPDATE(
266     I duIce, dvIce,
267 mlosch 1.15 U uIce, vIce, JFNKresidual,
268     O uIceRes, vIceRes,
269     I newtonIter, myTime, myIter, myThid )
270     C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
271 mlosch 1.1 DO bj=myByLo(myThid),myByHi(myThid)
272     DO bi=myBxLo(myThid),myBxHi(myThid)
273 jmc 1.20 DO J=1-OLy,sNy+OLy
274     DO I=1-OLx,sNx+OLx
275 mlosch 1.4 duIce(I,J,bi,bj)= 0. _d 0
276     dvIce(I,J,bi,bj)= 0. _d 0
277 mlosch 1.1 ENDDO
278     ENDDO
279     ENDDO
280     ENDDO
281     ENDIF
282     C end of Newton iterate
283     ENDDO
284 jmc 1.20
285 mlosch 1.5 C-- Output diagnostics
286 jmc 1.20
287 mlosch 1.6 IF ( SEAICE_monFreq .GT. 0. _d 0 ) THEN
288 mlosch 1.5 C Count iterations
289 mlosch 1.6 totalJFNKtimeSteps = totalJFNKtimeSteps + 1
290     totalNewtonIters = totalNewtonIters + newtonIter
291     totalKrylovIters = totalKrylovIters + totalKrylovItersLoc
292 mlosch 1.5 C Record failure
293 mlosch 1.6 totalKrylovFails = totalKrylovFails + krylovFails
294     IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
295 jmc 1.20 totalNewtonFails = totalNewtonFails + 1
296 mlosch 1.6 ENDIF
297 mlosch 1.5 ENDIF
298     C Decide whether it is time to dump and reset the counter
299 mlosch 1.9 writeNow = DIFFERENT_MULTIPLE(SEAICE_monFreq,
300 jmc 1.20 & myTime+deltaTClock, deltaTClock)
301 mlosch 1.9 #ifdef ALLOW_CAL
302     IF ( useCAL ) THEN
303 jmc 1.20 CALL CAL_TIME2DUMP(
304 mlosch 1.9 I zeroRL, SEAICE_monFreq, deltaTClock,
305     U writeNow,
306     I myTime+deltaTclock, myIter+1, myThid )
307     ENDIF
308     #endif
309     IF ( writeNow ) THEN
310 mlosch 1.5 _BEGIN_MASTER( myThid )
311 jmc 1.20 WRITE(msgBuf,'(A)')
312 mlosch 1.5 &' // ======================================================='
313     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
314     & SQUEEZE_RIGHT, myThid )
315     WRITE(msgBuf,'(A)') ' // Begin JFNK statistics'
316     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
317     & SQUEEZE_RIGHT, myThid )
318 jmc 1.20 WRITE(msgBuf,'(A)')
319 mlosch 1.5 &' // ======================================================='
320     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
321     & SQUEEZE_RIGHT, myThid )
322 jmc 1.20 WRITE(msgBuf,'(A,I10)')
323 mlosch 1.5 & ' %JFNK_MON: time step = ', myIter+1
324     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
325     & SQUEEZE_RIGHT, myThid )
326 jmc 1.20 WRITE(msgBuf,'(A,I10)')
327 mlosch 1.5 & ' %JFNK_MON: Nb. of time steps = ', totalJFNKtimeSteps
328     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
329     & SQUEEZE_RIGHT, myThid )
330 jmc 1.20 WRITE(msgBuf,'(A,I10)')
331 mlosch 1.5 & ' %JFNK_MON: Nb. of Newton steps = ', totalNewtonIters
332     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
333     & SQUEEZE_RIGHT, myThid )
334 jmc 1.20 WRITE(msgBuf,'(A,I10)')
335 mlosch 1.5 & ' %JFNK_MON: Nb. of Krylov steps = ', totalKrylovIters
336     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
337     & SQUEEZE_RIGHT, myThid )
338 jmc 1.20 WRITE(msgBuf,'(A,I10)')
339 mlosch 1.5 & ' %JFNK_MON: Nb. of Newton failures = ', totalNewtonFails
340     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
341     & SQUEEZE_RIGHT, myThid )
342 jmc 1.20 WRITE(msgBuf,'(A,I10)')
343 mlosch 1.5 & ' %JFNK_MON: Nb. of Krylov failures = ', totalKrylovFails
344     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
345     & SQUEEZE_RIGHT, myThid )
346 jmc 1.20 WRITE(msgBuf,'(A)')
347 mlosch 1.5 &' // ======================================================='
348     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
349     & SQUEEZE_RIGHT, myThid )
350 mlosch 1.11 WRITE(msgBuf,'(A)') ' // End JFNK statistics'
351 mlosch 1.5 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
352     & SQUEEZE_RIGHT, myThid )
353 jmc 1.20 WRITE(msgBuf,'(A)')
354 mlosch 1.5 &' // ======================================================='
355     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
356     & SQUEEZE_RIGHT, myThid )
357     _END_MASTER( myThid )
358     C reset and start again
359     totalJFNKtimeSteps = 0
360     totalNewtonIters = 0
361     totalKrylovIters = 0
362     totalKrylovFails = 0
363     totalNewtonFails = 0
364     ENDIF
365    
366     C Print more debugging information
367 mlosch 1.1 IF ( debugLevel.GE.debLevA ) THEN
368     IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
369 mlosch 1.5 _BEGIN_MASTER( myThid )
370 jmc 1.20 WRITE(msgBuf,'(A,I10)')
371 mlosch 1.1 & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
372 mlosch 1.5 & myIter+1
373 mlosch 1.1 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
374     & SQUEEZE_RIGHT, myThid )
375 mlosch 1.5 _END_MASTER( myThid )
376 mlosch 1.1 ENDIF
377 mlosch 1.5 IF ( krylovFails .GT. 0 ) THEN
378     _BEGIN_MASTER( myThid )
379 jmc 1.20 WRITE(msgBuf,'(A,I4,A,I10)')
380 mlosch 1.1 & ' S/R SEAICE_JFNK: FGMRES did not converge ',
381 mlosch 1.5 & krylovFails, ' times in timestep ', myIter+1
382 mlosch 1.1 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
383     & SQUEEZE_RIGHT, myThid )
384 mlosch 1.5 _END_MASTER( myThid )
385 mlosch 1.1 ENDIF
386 mlosch 1.5 _BEGIN_MASTER( myThid )
387 jmc 1.20 WRITE(msgBuf,'(A,I6,A,I10)')
388 mlosch 1.1 & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
389 mlosch 1.5 & totalKrylovItersLoc, ' in timestep ', myIter+1
390     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
391     & SQUEEZE_RIGHT, myThid )
392     _END_MASTER( myThid )
393 mlosch 1.1 ENDIF
394    
395 mlosch 1.15 RETURN
396     END
397    
398 mlosch 1.16 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
399 mlosch 1.15 CBOP
400     C !ROUTINE: SEAICE_JFNK_UPDATE
401     C !INTERFACE:
402    
403 jmc 1.20 SUBROUTINE SEAICE_JFNK_UPDATE(
404     I duIce, dvIce,
405 mlosch 1.15 U uIce, vIce, JFNKresidual,
406     O uIceRes, vIceRes,
407     I newtonIter, myTime, myIter, myThid )
408    
409     C !DESCRIPTION: \bv
410     C *==========================================================*
411     C | SUBROUTINE SEAICE_JFNK_UPDATE
412     C | o Update velocities with incremental solutions of FGMRES
413     C | o compute residual of updated solutions and do
414     C | o linesearch:
415     C | reduce update until residual is smaller than previous
416     C | one (input)
417     C *==========================================================*
418     C | written by Martin Losch, Jan 2013
419     C *==========================================================*
420     C \ev
421    
422     C !USES:
423     IMPLICIT NONE
424    
425     C === Global variables ===
426     #include "SIZE.h"
427     #include "EEPARAMS.h"
428     #include "PARAMS.h"
429     #include "SEAICE_SIZE.h"
430     #include "SEAICE_PARAMS.h"
431    
432     C !INPUT/OUTPUT PARAMETERS:
433     C === Routine arguments ===
434     C myTime :: Simulation time
435     C myIter :: Simulation timestep number
436     C myThid :: my Thread Id. number
437     C newtonIter :: current iterate of Newton iteration
438     _RL myTime
439     INTEGER myIter
440     INTEGER myThid
441     INTEGER newtonIter
442     C JFNKresidual :: Residual at the beginning of the FGMRES iteration,
443     C changes with newtonIter (updated)
444     _RL JFNKresidual
445     C du/vIce :: ice velocity increment to be added to u/vIce (input)
446     _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
447     _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
448     C u/vIce :: ice velocity increment to be added to u/vIce (updated)
449     _RL uIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
450     _RL vIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
451     C u/vIceRes :: residual of sea-ice momentum equations (output)
452     _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
453     _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
454    
455 mlosch 1.16 C !LOCAL VARIABLES:
456     C === Local variables ===
457 mlosch 1.15 C i,j,bi,bj :: loop indices
458     INTEGER i,j,bi,bj
459     INTEGER l
460     _RL resLoc, facLS
461     LOGICAL doLineSearch
462     C nVec :: size of the input vector(s)
463 jmc 1.20 C resTmp :: vector version of the residuals
464 mlosch 1.15 INTEGER nVec
465     PARAMETER ( nVec = 2*sNx*sNy )
466     _RL resTmp (nVec,1,nSx,nSy)
467 jmc 1.20
468 mlosch 1.15 CHARACTER*(MAX_LEN_MBUF) msgBuf
469     CEOP
470    
471     C Initialise some local variables
472     l = 0
473     resLoc = JFNKresidual
474     facLS = 1. _d 0
475     doLineSearch = .TRUE.
476     DO WHILE ( doLineSearch )
477     C Create update
478     DO bj=myByLo(myThid),myByHi(myThid)
479     DO bi=myBxLo(myThid),myBxHi(myThid)
480 jmc 1.20 DO J=1-OLy,sNy+OLy
481     DO I=1-OLx,sNx+OLx
482 mlosch 1.15 uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
483     vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
484     ENDDO
485     ENDDO
486     ENDDO
487     ENDDO
488     C Compute current residual F(u), (includes re-computation of global
489     C variables DWATN, zeta, and eta, i.e. they are different after this)
490 jmc 1.20 CALL SEAICE_CALC_RESIDUAL(
491     I uIce, vIce,
492     O uIceRes, vIceRes,
493 mlosch 1.15 I newtonIter, 0, myTime, myIter, myThid )
494     C Important: Compute the norm of the residual using the same scalar
495     C product that SEAICE_FGMRES does
496     CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
497     CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
498     resLoc = SQRT(resLoc)
499 mlosch 1.19 C Determine, if we need more iterations
500 jmc 1.20 doLineSearch = resLoc .GE. JFNKresidual
501 mlosch 1.19 C Limit the maximum number of iterations arbitrarily to four
502 jmc 1.20 doLineSearch = doLineSearch .AND. l .LT. 4
503 mlosch 1.19 C For the first iteration du/vIce = 0 and there will be no
504     C improvement of the residual possible, so we do only the first
505     C iteration
506     IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
507     C Only start a linesearch after some Newton iterations
508     IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
509     C Increment counter
510     l = l + 1
511 mlosch 1.15 C some output diagnostics
512     IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
513     _BEGIN_MASTER( myThid )
514 jmc 1.20 WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
515 mlosch 1.15 & ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
516     & 'facLS, JFNKresidual, resLoc = ',
517     & newtonIter, l, facLS, JFNKresidual, resLoc
518     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
519     & SQUEEZE_RIGHT, myThid )
520     _END_MASTER( myThid )
521     ENDIF
522     C Get ready for the next iteration: after adding du/vIce in the first
523     C iteration, we substract 0.5*du/vIce from u/vIce in the next
524     C iterations, 0.25*du/vIce in the second, etc.
525     facLS = - 0.5 _d 0 * ABS(facLS)
526     ENDDO
527     C This is the new residual
528     JFNKresidual = resLoc
529    
530 mlosch 1.21 #endif /* SEAICE_ALLOW_JFNK */
531 mlosch 1.1
532     RETURN
533     END

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