/[MITgcm]/MITgcm/pkg/seaice/seaice_jfnk.F
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Revision 1.17 - (hide annotations) (download)
Thu Jan 17 10:42:43 2013 UTC (12 years, 6 months ago) by mlosch
Branch: MAIN
CVS Tags: checkpoint64c
Changes since 1.16: +8 -3 lines
 add a parameter JFNKres_tFac that can replace JFNKres_t
    (= JFNKres_tFac*JFNKresidual before JFNK solver)

1 mlosch 1.17 C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_jfnk.F,v 1.16 2013/01/17 08:51:15 mlosch 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     #if ( (defined SEAICE_CGRID) && \
57     (defined SEAICE_ALLOW_JFNK) && \
58     (defined SEAICE_ALLOW_DYNAMICS) )
59 mlosch 1.5 C !FUNCTIONS:
60     LOGICAL DIFFERENT_MULTIPLE
61     EXTERNAL DIFFERENT_MULTIPLE
62 mlosch 1.1
63 mlosch 1.16 C !LOCAL VARIABLES:
64     C === Local variables ===
65 mlosch 1.1 C i,j,bi,bj :: loop indices
66     INTEGER i,j,bi,bj
67     C loop indices
68 mlosch 1.5 INTEGER newtonIter
69     INTEGER krylovIter, krylovFails
70 mlosch 1.13 INTEGER totalKrylovItersLoc, totalNewtonItersLoc
71 mlosch 1.5 C FGMRES flag that determines amount of output messages of fgmres
72     INTEGER iOutFGMRES
73     C FGMRES flag that indicates what fgmres wants us to do next
74 mlosch 1.1 INTEGER iCode
75 mlosch 1.13 _RL JFNKresidual
76 mlosch 1.1 _RL JFNKresidualKm1
77     C parameters to compute convergence criterion
78     _RL phi_e, alp_e, JFNKgamma_lin
79     _RL FGMRESeps
80     _RL JFNKtol
81     C
82     _RL recip_deltaT
83     LOGICAL JFNKconverged, krylovConverged
84 mlosch 1.9 LOGICAL writeNow
85 mlosch 1.1 CHARACTER*(MAX_LEN_MBUF) msgBuf
86     C
87     C u/vIceRes :: residual of sea-ice momentum equations
88     _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
89     _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
90 mlosch 1.14 C vector version of the residuals
91     _RL resTmp (nVec,1,nSx,nSy)
92 mlosch 1.1 C du/vIce :: ice velocity increment to be added to u/vIce
93     _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
94     _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
95     C precomputed (= constant per Newton iteration) versions of
96 mlosch 1.2 C zeta, eta, and DWATN, press
97     _RL zetaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
98     _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
99 mlosch 1.8 _RL etaZPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
100 mlosch 1.2 _RL dwatPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
101 mlosch 1.1 CEOP
102    
103     C Initialise
104 mlosch 1.5 newtonIter = 0
105     krylovFails = 0
106     totalKrylovItersLoc = 0
107     JFNKconverged = .FALSE.
108     JFNKtol = 0. _d 0
109     JFNKresidual = 0. _d 0
110     JFNKresidualKm1 = 0. _d 0
111     FGMRESeps = 0. _d 0
112     recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
113    
114     iOutFGMRES=0
115 mlosch 1.12 C with iOutFgmres=1, seaice_fgmres prints the residual at each iteration
116     IF ( debugLevel.GE.debLevC .AND.
117 mlosch 1.5 & DIFFERENT_MULTIPLE( SEAICE_monFreq, myTime, deltaTClock ) )
118     & iOutFGMRES=1
119    
120 mlosch 1.1 C
121     DO bj=myByLo(myThid),myByHi(myThid)
122     DO bi=myBxLo(myThid),myBxHi(myThid)
123     DO J=1-Oly,sNy+Oly
124     DO I=1-Olx,sNx+Olx
125     uIceRes(I,J,bi,bj) = 0. _d 0
126     vIceRes(I,J,bi,bj) = 0. _d 0
127     duIce (I,J,bi,bj) = 0. _d 0
128     dvIce (I,J,bi,bj) = 0. _d 0
129     uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
130     vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
131     ENDDO
132     ENDDO
133     C Compute things that do no change during the Newton iteration:
134     C sea-surface tilt and wind stress:
135     C FORCEX/Y0 - mass*(u/vIceNm1)/deltaT
136     DO J=1-Oly,sNy+Oly
137     DO I=1-Olx,sNx+Olx
138     FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
139     & + seaiceMassU(I,J,bi,bj)*uIceNm1(I,J,bi,bj)*recip_deltaT
140     FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
141     & + seaiceMassV(I,J,bi,bj)*vIceNm1(I,J,bi,bj)*recip_deltaT
142     ENDDO
143     ENDDO
144     ENDDO
145     ENDDO
146     C Start nonlinear Newton iteration: outer loop iteration
147     DO WHILE ( newtonIter.LT.SEAICEnewtonIterMax .AND.
148     & .NOT.JFNKconverged )
149     newtonIter = newtonIter + 1
150     C Compute initial residual F(u), (includes computation of global
151     C variables DWATN, zeta, and eta)
152 mlosch 1.16 IF ( newtonIter .EQ. 1 ) CALL SEAICE_JFNK_UPDATE(
153 mlosch 1.15 I duIce, dvIce,
154     U uIce, vIce, JFNKresidual,
155     O uIceRes, vIceRes,
156     I newtonIter, myTime, myIter, myThid )
157 mlosch 1.1 C local copies of precomputed coefficients that are to stay
158     C constant for the preconditioner
159     DO bj=myByLo(myThid),myByHi(myThid)
160     DO bi=myBxLo(myThid),myBxHi(myThid)
161     DO j=1-Oly,sNy+Oly
162     DO i=1-Olx,sNx+Olx
163 mlosch 1.10 zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
164     etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
165     etaZPre(I,J,bi,bj) = etaZ(I,J,bi,bj)
166     dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
167 mlosch 1.1 ENDDO
168     ENDDO
169     ENDDO
170     ENDDO
171     C compute convergence criterion for linear preconditioned FGMRES
172     JFNKgamma_lin = JFNKgamma_lin_max
173     IF ( newtonIter.GT.1.AND.newtonIter.LE.100
174     & .AND.JFNKresidual.LT.JFNKres_t ) THEN
175     C Eisenstat, 1996, equ.(2.6)
176     phi_e = 1. _d 0
177     alp_e = 1. _d 0
178     JFNKgamma_lin = phi_e*( JFNKresidual/JFNKresidualKm1 )**alp_e
179     JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
180     JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
181     ENDIF
182     C save the residual for the next iteration
183     JFNKresidualKm1 = JFNKresidual
184     C
185     C The Krylov iteration using FGMRES, the preconditioner is LSOR
186     C for now. The code is adapted from SEAICE_LSR, but heavily stripped
187     C down.
188     C krylovIter is mapped into "its" in seaice_fgmres and is incremented
189     C in that routine
190     krylovIter = 0
191     iCode = 0
192     C
193     JFNKconverged = JFNKresidual.LT.JFNKtol
194     C
195     C do Krylov loop only if convergence is not reached
196     C
197     IF ( .NOT.JFNKconverged ) THEN
198     C
199     C start Krylov iteration (FGMRES)
200     C
201     krylovConverged = .FALSE.
202     FGMRESeps = JFNKgamma_lin * JFNKresidual
203     DO WHILE ( .NOT.krylovConverged )
204     C solution vector sol = du/vIce
205     C residual vector (rhs) Fu = u/vIceRes
206     C output work vectors wk1, -> input work vector wk2
207     C
208     CALL SEAICE_FGMRES_DRIVER(
209     I uIceRes, vIceRes,
210     U duIce, dvIce, iCode,
211 mlosch 1.5 I FGMRESeps, iOutFGMRES,
212 mlosch 1.1 I newtonIter, krylovIter, myTime, myIter, myThid )
213     C FGMRES returns iCode either asking for an new preconditioned vector
214     C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
215     C iteration
216     IF (iCode.EQ.1) THEN
217 mlosch 1.7 C Call preconditioner
218     IF ( SOLV_MAX_ITERS .GT. 0 )
219     & CALL SEAICE_PRECONDITIONER(
220 mlosch 1.1 U duIce, dvIce,
221 mlosch 1.10 I zetaPre, etaPre, etaZpre, dwatPre,
222 mlosch 1.1 I newtonIter, krylovIter, myTime, myIter, myThid )
223     ELSEIF (iCode.GE.2) THEN
224     C Compute Jacobian times vector
225     CALL SEAICE_JACVEC(
226     I uIce, vIce, uIceRes, vIceRes,
227     U duIce, dvIce,
228     I newtonIter, krylovIter, myTime, myIter, myThid )
229     ENDIF
230     krylovConverged = iCode.EQ.0
231     C End of Krylov iterate
232     ENDDO
233 mlosch 1.5 totalKrylovItersLoc = totalKrylovItersLoc + krylovIter
234 mlosch 1.1 C some output diagnostics
235     IF ( debugLevel.GE.debLevA ) THEN
236 mlosch 1.5 _BEGIN_MASTER( myThid )
237 mlosch 1.13 totalNewtonItersLoc =
238     & SEAICEnewtonIterMax*(myIter-nIter0)+newtonIter
239     WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
240     & ' S/R SEAICE_JFNK: Newton iterate / total, ',
241     & 'JFNKgamma_lin, initial norm = ',
242     & newtonIter, totalNewtonItersLoc,
243     & JFNKgamma_lin,JFNKresidual
244     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
245     & SQUEEZE_RIGHT, myThid )
246 mlosch 1.1 WRITE(msgBuf,'(3(A,I6))')
247 mlosch 1.13 & ' S/R SEAICE_JFNK: Newton iterate / total = ',newtonIter,
248     & ' / ', totalNewtonItersLoc,
249 mlosch 1.1 & ', Nb. of FGMRES iterations = ', krylovIter
250     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
251     & SQUEEZE_RIGHT, myThid )
252 mlosch 1.5 _END_MASTER( myThid )
253 mlosch 1.1 ENDIF
254     IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN
255 mlosch 1.5 krylovFails = krylovFails + 1
256 mlosch 1.1 ENDIF
257 mlosch 1.17 C Set the stopping criterion for the Newton iteration and the
258     C criterion for the transition from accurate to approximate FGMRES
259     IF ( newtonIter .EQ. 1 ) THEN
260     JFNKtol=JFNKgamma_nonlin*JFNKresidual
261     IF ( JFNKres_tFac .NE. UNSET_RL )
262     & JFNKres_t = JFNKresidual * JFNKres_tFac
263     ENDIF
264 mlosch 1.1 C Update linear solution vector and return to Newton iteration
265 mlosch 1.15 C Do a linesearch if necessary, and compute a new residual.
266     C Note that it should be possible to do the following operations
267     C at the beginning of the Newton iteration, thereby saving us from
268     C the extra call of seaice_jfnk_update, but unfortunately that
269     C changes the results, so we leave the stuff here for now.
270     CALL SEAICE_JFNK_UPDATE(
271     I duIce, dvIce,
272     U uIce, vIce, JFNKresidual,
273     O uIceRes, vIceRes,
274     I newtonIter, myTime, myIter, myThid )
275     C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
276 mlosch 1.1 DO bj=myByLo(myThid),myByHi(myThid)
277     DO bi=myBxLo(myThid),myBxHi(myThid)
278     DO J=1-Oly,sNy+Oly
279     DO I=1-Olx,sNx+Olx
280 mlosch 1.4 duIce(I,J,bi,bj)= 0. _d 0
281     dvIce(I,J,bi,bj)= 0. _d 0
282 mlosch 1.1 ENDDO
283     ENDDO
284     ENDDO
285     ENDDO
286     ENDIF
287     C end of Newton iterate
288     ENDDO
289 mlosch 1.5 C
290     C-- Output diagnostics
291     C
292 mlosch 1.6 IF ( SEAICE_monFreq .GT. 0. _d 0 ) THEN
293 mlosch 1.5 C Count iterations
294 mlosch 1.6 totalJFNKtimeSteps = totalJFNKtimeSteps + 1
295     totalNewtonIters = totalNewtonIters + newtonIter
296     totalKrylovIters = totalKrylovIters + totalKrylovItersLoc
297 mlosch 1.5 C Record failure
298 mlosch 1.6 totalKrylovFails = totalKrylovFails + krylovFails
299     IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
300     totalNewtonFails = totalNewtonFails + 1
301     ENDIF
302 mlosch 1.5 ENDIF
303     C Decide whether it is time to dump and reset the counter
304 mlosch 1.9 writeNow = DIFFERENT_MULTIPLE(SEAICE_monFreq,
305     & myTime+deltaTClock, deltaTClock)
306     #ifdef ALLOW_CAL
307     IF ( useCAL ) THEN
308     CALL CAL_TIME2DUMP(
309     I zeroRL, SEAICE_monFreq, deltaTClock,
310     U writeNow,
311     I myTime+deltaTclock, myIter+1, myThid )
312     ENDIF
313     #endif
314     IF ( writeNow ) THEN
315 mlosch 1.5 _BEGIN_MASTER( myThid )
316     WRITE(msgBuf,'(A)')
317     &' // ======================================================='
318     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
319     & SQUEEZE_RIGHT, myThid )
320     WRITE(msgBuf,'(A)') ' // Begin JFNK statistics'
321     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
322     & SQUEEZE_RIGHT, myThid )
323     WRITE(msgBuf,'(A)')
324     &' // ======================================================='
325     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
326     & SQUEEZE_RIGHT, myThid )
327     WRITE(msgBuf,'(A,I10)')
328     & ' %JFNK_MON: time step = ', myIter+1
329     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
330     & SQUEEZE_RIGHT, myThid )
331     WRITE(msgBuf,'(A,I10)')
332     & ' %JFNK_MON: Nb. of time steps = ', totalJFNKtimeSteps
333     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
334     & SQUEEZE_RIGHT, myThid )
335     WRITE(msgBuf,'(A,I10)')
336     & ' %JFNK_MON: Nb. of Newton steps = ', totalNewtonIters
337     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
338     & SQUEEZE_RIGHT, myThid )
339     WRITE(msgBuf,'(A,I10)')
340     & ' %JFNK_MON: Nb. of Krylov steps = ', totalKrylovIters
341     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
342     & SQUEEZE_RIGHT, myThid )
343     WRITE(msgBuf,'(A,I10)')
344     & ' %JFNK_MON: Nb. of Newton failures = ', totalNewtonFails
345     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
346     & SQUEEZE_RIGHT, myThid )
347     WRITE(msgBuf,'(A,I10)')
348     & ' %JFNK_MON: Nb. of Krylov failures = ', totalKrylovFails
349     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
350     & SQUEEZE_RIGHT, myThid )
351     WRITE(msgBuf,'(A)')
352     &' // ======================================================='
353     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
354     & SQUEEZE_RIGHT, myThid )
355 mlosch 1.11 WRITE(msgBuf,'(A)') ' // End JFNK statistics'
356 mlosch 1.5 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
357     & SQUEEZE_RIGHT, myThid )
358     WRITE(msgBuf,'(A)')
359     &' // ======================================================='
360     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
361     & SQUEEZE_RIGHT, myThid )
362     _END_MASTER( myThid )
363     C reset and start again
364     totalJFNKtimeSteps = 0
365     totalNewtonIters = 0
366     totalKrylovIters = 0
367     totalKrylovFails = 0
368     totalNewtonFails = 0
369     ENDIF
370    
371     C Print more debugging information
372 mlosch 1.1 IF ( debugLevel.GE.debLevA ) THEN
373     IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
374 mlosch 1.5 _BEGIN_MASTER( myThid )
375 mlosch 1.1 WRITE(msgBuf,'(A,I10)')
376     & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
377 mlosch 1.5 & myIter+1
378 mlosch 1.1 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
379     & SQUEEZE_RIGHT, myThid )
380 mlosch 1.5 _END_MASTER( myThid )
381 mlosch 1.1 ENDIF
382 mlosch 1.5 IF ( krylovFails .GT. 0 ) THEN
383     _BEGIN_MASTER( myThid )
384 mlosch 1.1 WRITE(msgBuf,'(A,I4,A,I10)')
385     & ' S/R SEAICE_JFNK: FGMRES did not converge ',
386 mlosch 1.5 & krylovFails, ' times in timestep ', myIter+1
387 mlosch 1.1 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
388     & SQUEEZE_RIGHT, myThid )
389 mlosch 1.5 _END_MASTER( myThid )
390 mlosch 1.1 ENDIF
391 mlosch 1.5 _BEGIN_MASTER( myThid )
392     WRITE(msgBuf,'(A,I6,A,I10)')
393 mlosch 1.1 & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
394 mlosch 1.5 & totalKrylovItersLoc, ' in timestep ', myIter+1
395     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
396     & SQUEEZE_RIGHT, myThid )
397     _END_MASTER( myThid )
398 mlosch 1.1 ENDIF
399    
400 mlosch 1.15 RETURN
401     END
402    
403 mlosch 1.16 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
404 mlosch 1.15 CBOP
405     C !ROUTINE: SEAICE_JFNK_UPDATE
406     C !INTERFACE:
407    
408     SUBROUTINE SEAICE_JFNK_UPDATE(
409     I duIce, dvIce,
410     U uIce, vIce, JFNKresidual,
411     O uIceRes, vIceRes,
412     I newtonIter, myTime, myIter, myThid )
413    
414     C !DESCRIPTION: \bv
415     C *==========================================================*
416     C | SUBROUTINE SEAICE_JFNK_UPDATE
417     C | o Update velocities with incremental solutions of FGMRES
418     C | o compute residual of updated solutions and do
419     C | o linesearch:
420     C | reduce update until residual is smaller than previous
421     C | one (input)
422     C *==========================================================*
423     C | written by Martin Losch, Jan 2013
424     C *==========================================================*
425     C \ev
426    
427     C !USES:
428     IMPLICIT NONE
429    
430     C === Global variables ===
431     #include "SIZE.h"
432     #include "EEPARAMS.h"
433     #include "PARAMS.h"
434     #include "SEAICE_SIZE.h"
435     #include "SEAICE_PARAMS.h"
436    
437     C !INPUT/OUTPUT PARAMETERS:
438     C === Routine arguments ===
439     C myTime :: Simulation time
440     C myIter :: Simulation timestep number
441     C myThid :: my Thread Id. number
442     C newtonIter :: current iterate of Newton iteration
443     _RL myTime
444     INTEGER myIter
445     INTEGER myThid
446     INTEGER newtonIter
447     C JFNKresidual :: Residual at the beginning of the FGMRES iteration,
448     C changes with newtonIter (updated)
449     _RL JFNKresidual
450     C du/vIce :: ice velocity increment to be added to u/vIce (input)
451     _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
452     _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
453     C u/vIce :: ice velocity increment to be added to u/vIce (updated)
454     _RL uIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
455     _RL vIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
456     C u/vIceRes :: residual of sea-ice momentum equations (output)
457     _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
458     _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
459    
460 mlosch 1.16 C !LOCAL VARIABLES:
461     C === Local variables ===
462 mlosch 1.15 C i,j,bi,bj :: loop indices
463     INTEGER i,j,bi,bj
464     INTEGER l
465     _RL resLoc, facLS
466     LOGICAL doLineSearch
467     C nVec :: size of the input vector(s)
468     C vector version of the residuals
469     INTEGER nVec
470     PARAMETER ( nVec = 2*sNx*sNy )
471     _RL resTmp (nVec,1,nSx,nSy)
472     C
473     CHARACTER*(MAX_LEN_MBUF) msgBuf
474     CEOP
475    
476     C Initialise some local variables
477     l = 0
478     resLoc = JFNKresidual
479     facLS = 1. _d 0
480     doLineSearch = .TRUE.
481     DO WHILE ( doLineSearch )
482     C Determine, if we need more iterations
483     doLineSearch = resLoc .GE. JFNKresidual
484 mlosch 1.16 C Limit the maximum number of iterations arbitrarily to four
485 mlosch 1.15 doLineSearch = doLineSearch .AND. l .LE. 4
486     C For the first iteration du/vIce = 0 and there will be no
487     C improvement of the residual possible, so we do only the first
488     C iteration
489     IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
490     C Only start a linesearch after some Newton iterations
491     IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
492     C Increment counter
493     l = l + 1
494     C Create update
495     DO bj=myByLo(myThid),myByHi(myThid)
496     DO bi=myBxLo(myThid),myBxHi(myThid)
497     DO J=1-Oly,sNy+Oly
498     DO I=1-Olx,sNx+Olx
499     uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
500     vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
501     ENDDO
502     ENDDO
503     ENDDO
504     ENDDO
505     C Compute current residual F(u), (includes re-computation of global
506     C variables DWATN, zeta, and eta, i.e. they are different after this)
507     CALL SEAICE_CALC_RESIDUAL(
508     I uIce, vIce,
509     O uIceRes, vIceRes,
510     I newtonIter, 0, myTime, myIter, myThid )
511     C Important: Compute the norm of the residual using the same scalar
512     C product that SEAICE_FGMRES does
513     CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
514     CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
515     resLoc = SQRT(resLoc)
516     C some output diagnostics
517     IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
518     _BEGIN_MASTER( myThid )
519     WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
520     & ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
521     & 'facLS, JFNKresidual, resLoc = ',
522     & newtonIter, l, facLS, JFNKresidual, resLoc
523     CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
524     & SQUEEZE_RIGHT, myThid )
525     _END_MASTER( myThid )
526     ENDIF
527     C Get ready for the next iteration: after adding du/vIce in the first
528     C iteration, we substract 0.5*du/vIce from u/vIce in the next
529     C iterations, 0.25*du/vIce in the second, etc.
530     facLS = - 0.5 _d 0 * ABS(facLS)
531     ENDDO
532     C This is the new residual
533     JFNKresidual = resLoc
534    
535 mlosch 1.1 #endif /* SEAICE_ALLOW_DYNAMICS and SEAICE_CGRID and SEAICE_ALLOW_JFNK */
536    
537     RETURN
538     END

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