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Revision 1.26 - (show annotations) (download)
Thu Mar 20 09:24:49 2014 UTC (11 years, 3 months ago) by mlosch
Branch: MAIN
CVS Tags: checkpoint64y, checkpoint64x, checkpoint64z, checkpoint64w, checkpoint64v, checkpoint65b, checkpoint65c, checkpoint65a, checkpoint65f, checkpoint65d, checkpoint65e, checkpoint65
Changes since 1.25: +4 -3 lines
comment out if-statement related to IMEX to avoid suprises

1 C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_jfnk.F,v 1.25 2014/02/07 14:27:21 mlosch Exp $
2 C $Name: $
3
4 #include "SEAICE_OPTIONS.h"
5
6 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 CBOP
12 C !ROUTINE: SEAICE_JFNK
13 C !INTERFACE:
14 SUBROUTINE SEAICE_JFNK( myTime, myIter, myThid )
15
16 C !DESCRIPTION: \bv
17 C *==========================================================*
18 C | SUBROUTINE SEAICE_JFNK
19 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 #ifdef SEAICE_ALLOW_JFNK
57 C !FUNCTIONS:
58 LOGICAL DIFFERENT_MULTIPLE
59 EXTERNAL DIFFERENT_MULTIPLE
60
61 C !LOCAL VARIABLES:
62 C === Local variables ===
63 C i,j,bi,bj :: loop indices
64 INTEGER i,j,bi,bj
65 C loop indices
66 INTEGER newtonIter
67 INTEGER krylovIter, krylovFails
68 INTEGER totalKrylovItersLoc, totalNewtonItersLoc
69 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 INTEGER iCode
73 _RL JFNKresidual
74 _RL JFNKresidualKm1
75 C parameters to compute convergence criterion
76 _RL JFNKgamma_lin
77 _RL FGMRESeps
78 _RL JFNKtol
79 C backward differences extrapolation factors
80 _RL bdfFac, bdfAlpha
81 C
82 _RL recip_deltaT
83 LOGICAL JFNKconverged, krylovConverged
84 LOGICAL writeNow
85 CHARACTER*(MAX_LEN_MBUF) msgBuf
86
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 C extra time level required for backward difference time stepping
91 _RL duIcNm1(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
92 _RL dvIcNm1(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
93 C du/vIce :: ice velocity increment to be added to u/vIce
94 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
95 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
96 C precomputed (= constant per Newton iteration) versions of
97 C zeta, eta, and DWATN, press
98 _RL zetaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
99 _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
100 _RL etaZPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
101 _RL dwatPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
102 CEOP
103
104 C Initialise
105 newtonIter = 0
106 krylovFails = 0
107 totalKrylovItersLoc = 0
108 JFNKconverged = .FALSE.
109 JFNKtol = 0. _d 0
110 JFNKresidual = 0. _d 0
111 JFNKresidualKm1 = 0. _d 0
112 FGMRESeps = 0. _d 0
113 recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
114
115 iOutFGMRES=0
116 C with iOutFgmres=1, seaice_fgmres prints the residual at each iteration
117 IF ( debugLevel.GE.debLevC .AND.
118 & DIFFERENT_MULTIPLE( SEAICE_monFreq, myTime, deltaTClock ) )
119 & iOutFGMRES=1
120
121 C backward difference extrapolation factors
122 bdfFac = 0. _d 0
123 IF ( SEAICEuseBDF2 ) THEN
124 IF ( myIter.EQ.nIter0 .AND. SEAICEmomStartBDF.EQ.0 ) THEN
125 bdfFac = 0. _d 0
126 ELSE
127 bdfFac = 0.5 _d 0
128 ENDIF
129 ENDIF
130 bdfAlpha = 1. _d 0 + bdfFac
131
132 DO bj=myByLo(myThid),myByHi(myThid)
133 DO bi=myBxLo(myThid),myBxHi(myThid)
134 DO J=1-OLy,sNy+OLy
135 DO I=1-OLx,sNx+OLx
136 uIceRes(I,J,bi,bj) = 0. _d 0
137 vIceRes(I,J,bi,bj) = 0. _d 0
138 duIce (I,J,bi,bj) = 0. _d 0
139 dvIce (I,J,bi,bj) = 0. _d 0
140 ENDDO
141 ENDDO
142 C cycle ice velocities
143 DO J=1-OLy,sNy+OLy
144 DO I=1-OLx,sNx+OLx
145 duIcNm1(I,J,bi,bj) = uIce(I,J,bi,bj) * bdfAlpha
146 & + ( uIce(I,J,bi,bj) - uIceNm1(I,J,bi,bj) ) * bdfFac
147 dvIcNm1(I,J,bi,bj) = vIce(I,J,bi,bj) * bdfAlpha
148 & + ( vIce(I,J,bi,bj) - vIceNm1(I,J,bi,bj) ) * bdfFac
149 uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
150 vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
151 ENDDO
152 ENDDO
153 C As long as IMEX is not properly implemented leave this commented out
154 CML IF ( .NOT.SEAICEuseIMEX ) THEN
155 C Compute things that do no change during the Newton iteration:
156 C sea-surface tilt and wind stress:
157 C FORCEX/Y0 - mass*(1.5*u/vIceNm1+0.5*(u/vIceNm1-u/vIceNm2))/deltaT
158 DO J=1-OLy,sNy+OLy
159 DO I=1-OLx,sNx+OLx
160 FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
161 & + seaiceMassU(I,J,bi,bj)*duIcNm1(I,J,bi,bj)*recip_deltaT
162 FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
163 & + seaiceMassV(I,J,bi,bj)*dvIcNm1(I,J,bi,bj)*recip_deltaT
164 ENDDO
165 ENDDO
166 CML ENDIF
167 ENDDO
168 ENDDO
169 C Start nonlinear Newton iteration: outer loop iteration
170 DO WHILE ( newtonIter.LT.SEAICEnewtonIterMax .AND.
171 & .NOT.JFNKconverged )
172 newtonIter = newtonIter + 1
173 C Compute initial residual F(u), (includes computation of global
174 C variables DWATN, zeta, and eta)
175 IF ( newtonIter .EQ. 1 ) CALL SEAICE_JFNK_UPDATE(
176 I duIce, dvIce,
177 U uIce, vIce, JFNKresidual,
178 O uIceRes, vIceRes,
179 I newtonIter, myTime, myIter, myThid )
180 C local copies of precomputed coefficients that are to stay
181 C constant for the preconditioner
182 DO bj=myByLo(myThid),myByHi(myThid)
183 DO bi=myBxLo(myThid),myBxHi(myThid)
184 DO j=1-OLy,sNy+OLy
185 DO i=1-OLx,sNx+OLx
186 zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
187 etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
188 etaZPre(I,J,bi,bj) = etaZ(I,J,bi,bj)
189 dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
190 ENDDO
191 ENDDO
192 ENDDO
193 ENDDO
194 C compute convergence criterion for linear preconditioned FGMRES
195 JFNKgamma_lin = JFNKgamma_lin_max
196 IF ( newtonIter.GT.1.AND.newtonIter.LE.SEAICE_JFNK_tolIter
197 & .AND.JFNKresidual.LT.JFNKres_t ) THEN
198 C Eisenstat and Walker (1996), eq.(2.6)
199 JFNKgamma_lin = SEAICE_JFNKphi
200 & *( JFNKresidual/JFNKresidualKm1 )**SEAICE_JFNKalpha
201 JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
202 JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
203 ENDIF
204 C save the residual for the next iteration
205 JFNKresidualKm1 = JFNKresidual
206
207 C The Krylov iteration using FGMRES, the preconditioner is LSOR
208 C for now. The code is adapted from SEAICE_LSR, but heavily stripped
209 C down.
210 C krylovIter is mapped into "its" in seaice_fgmres and is incremented
211 C in that routine
212 krylovIter = 0
213 iCode = 0
214
215 JFNKconverged = JFNKresidual.LT.JFNKtol
216
217 C do Krylov loop only if convergence is not reached
218
219 IF ( .NOT.JFNKconverged ) THEN
220
221 C start Krylov iteration (FGMRES)
222
223 krylovConverged = .FALSE.
224 FGMRESeps = JFNKgamma_lin * JFNKresidual
225 DO WHILE ( .NOT.krylovConverged )
226 C solution vector sol = du/vIce
227 C residual vector (rhs) Fu = u/vIceRes
228 C output work vectors wk1, -> input work vector wk2
229
230 CALL SEAICE_FGMRES_DRIVER(
231 I uIceRes, vIceRes,
232 U duIce, dvIce, iCode,
233 I FGMRESeps, iOutFGMRES,
234 I newtonIter, krylovIter, myTime, myIter, myThid )
235 C FGMRES returns iCode either asking for an new preconditioned vector
236 C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
237 C iteration
238 IF (iCode.EQ.1) THEN
239 C Call preconditioner
240 IF ( SOLV_MAX_ITERS .GT. 0 )
241 & CALL SEAICE_PRECONDITIONER(
242 U duIce, dvIce,
243 I zetaPre, etaPre, etaZpre, dwatPre,
244 I newtonIter, krylovIter, myTime, myIter, myThid )
245 ELSEIF (iCode.GE.2) THEN
246 C Compute Jacobian times vector
247 CALL SEAICE_JACVEC(
248 I uIce, vIce, uIceRes, vIceRes,
249 U duIce, dvIce,
250 I newtonIter, krylovIter, myTime, myIter, myThid )
251 ENDIF
252 krylovConverged = iCode.EQ.0
253 C End of Krylov iterate
254 ENDDO
255 totalKrylovItersLoc = totalKrylovItersLoc + krylovIter
256 C some output diagnostics
257 IF ( debugLevel.GE.debLevA ) THEN
258 _BEGIN_MASTER( myThid )
259 totalNewtonItersLoc =
260 & SEAICEnewtonIterMax*(myIter-nIter0)+newtonIter
261 WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
262 & ' S/R SEAICE_JFNK: Newton iterate / total, ',
263 & 'JFNKgamma_lin, initial norm = ',
264 & newtonIter, totalNewtonItersLoc,
265 & JFNKgamma_lin,JFNKresidual
266 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
267 & SQUEEZE_RIGHT, myThid )
268 WRITE(msgBuf,'(3(A,I6))')
269 & ' S/R SEAICE_JFNK: Newton iterate / total = ',newtonIter,
270 & ' / ', totalNewtonItersLoc,
271 & ', Nb. of FGMRES iterations = ', krylovIter
272 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
273 & SQUEEZE_RIGHT, myThid )
274 _END_MASTER( myThid )
275 ENDIF
276 IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN
277 krylovFails = krylovFails + 1
278 ENDIF
279 C Set the stopping criterion for the Newton iteration and the
280 C criterion for the transition from accurate to approximate FGMRES
281 IF ( newtonIter .EQ. 1 ) THEN
282 JFNKtol=JFNKgamma_nonlin*JFNKresidual
283 IF ( JFNKres_tFac .NE. UNSET_RL )
284 & JFNKres_t = JFNKresidual * JFNKres_tFac
285 ENDIF
286 C Update linear solution vector and return to Newton iteration
287 C Do a linesearch if necessary, and compute a new residual.
288 C Note that it should be possible to do the following operations
289 C at the beginning of the Newton iteration, thereby saving us from
290 C the extra call of seaice_jfnk_update, but unfortunately that
291 C changes the results, so we leave the stuff here for now.
292 CALL SEAICE_JFNK_UPDATE(
293 I duIce, dvIce,
294 U uIce, vIce, JFNKresidual,
295 O uIceRes, vIceRes,
296 I newtonIter, myTime, myIter, myThid )
297 C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
298 DO bj=myByLo(myThid),myByHi(myThid)
299 DO bi=myBxLo(myThid),myBxHi(myThid)
300 DO J=1-OLy,sNy+OLy
301 DO I=1-OLx,sNx+OLx
302 duIce(I,J,bi,bj)= 0. _d 0
303 dvIce(I,J,bi,bj)= 0. _d 0
304 ENDDO
305 ENDDO
306 ENDDO
307 ENDDO
308 ENDIF
309 C end of Newton iterate
310 ENDDO
311
312 C-- Output diagnostics
313
314 IF ( SEAICE_monFreq .GT. 0. _d 0 ) THEN
315 C Count iterations
316 totalJFNKtimeSteps = totalJFNKtimeSteps + 1
317 totalNewtonIters = totalNewtonIters + newtonIter
318 totalKrylovIters = totalKrylovIters + totalKrylovItersLoc
319 C Record failure
320 totalKrylovFails = totalKrylovFails + krylovFails
321 IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
322 totalNewtonFails = totalNewtonFails + 1
323 ENDIF
324 ENDIF
325 C Decide whether it is time to dump and reset the counter
326 writeNow = DIFFERENT_MULTIPLE(SEAICE_monFreq,
327 & myTime+deltaTClock, deltaTClock)
328 #ifdef ALLOW_CAL
329 IF ( useCAL ) THEN
330 CALL CAL_TIME2DUMP(
331 I zeroRL, SEAICE_monFreq, deltaTClock,
332 U writeNow,
333 I myTime+deltaTclock, myIter+1, myThid )
334 ENDIF
335 #endif
336 IF ( writeNow ) THEN
337 _BEGIN_MASTER( myThid )
338 WRITE(msgBuf,'(A)')
339 &' // ======================================================='
340 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
341 & SQUEEZE_RIGHT, myThid )
342 WRITE(msgBuf,'(A)') ' // Begin JFNK statistics'
343 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
344 & SQUEEZE_RIGHT, myThid )
345 WRITE(msgBuf,'(A)')
346 &' // ======================================================='
347 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
348 & SQUEEZE_RIGHT, myThid )
349 WRITE(msgBuf,'(A,I10)')
350 & ' %JFNK_MON: time step = ', myIter+1
351 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
352 & SQUEEZE_RIGHT, myThid )
353 WRITE(msgBuf,'(A,I10)')
354 & ' %JFNK_MON: Nb. of time steps = ', totalJFNKtimeSteps
355 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
356 & SQUEEZE_RIGHT, myThid )
357 WRITE(msgBuf,'(A,I10)')
358 & ' %JFNK_MON: Nb. of Newton steps = ', totalNewtonIters
359 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
360 & SQUEEZE_RIGHT, myThid )
361 WRITE(msgBuf,'(A,I10)')
362 & ' %JFNK_MON: Nb. of Krylov steps = ', totalKrylovIters
363 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
364 & SQUEEZE_RIGHT, myThid )
365 WRITE(msgBuf,'(A,I10)')
366 & ' %JFNK_MON: Nb. of Newton failures = ', totalNewtonFails
367 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
368 & SQUEEZE_RIGHT, myThid )
369 WRITE(msgBuf,'(A,I10)')
370 & ' %JFNK_MON: Nb. of Krylov failures = ', totalKrylovFails
371 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
372 & SQUEEZE_RIGHT, myThid )
373 WRITE(msgBuf,'(A)')
374 &' // ======================================================='
375 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
376 & SQUEEZE_RIGHT, myThid )
377 WRITE(msgBuf,'(A)') ' // End JFNK statistics'
378 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
379 & SQUEEZE_RIGHT, myThid )
380 WRITE(msgBuf,'(A)')
381 &' // ======================================================='
382 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
383 & SQUEEZE_RIGHT, myThid )
384 _END_MASTER( myThid )
385 C reset and start again
386 totalJFNKtimeSteps = 0
387 totalNewtonIters = 0
388 totalKrylovIters = 0
389 totalKrylovFails = 0
390 totalNewtonFails = 0
391 ENDIF
392
393 C Print more debugging information
394 IF ( debugLevel.GE.debLevA ) THEN
395 IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
396 _BEGIN_MASTER( myThid )
397 WRITE(msgBuf,'(A,I10)')
398 & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
399 & myIter+1
400 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
401 & SQUEEZE_RIGHT, myThid )
402 _END_MASTER( myThid )
403 ENDIF
404 IF ( krylovFails .GT. 0 ) THEN
405 _BEGIN_MASTER( myThid )
406 WRITE(msgBuf,'(A,I4,A,I10)')
407 & ' S/R SEAICE_JFNK: FGMRES did not converge ',
408 & krylovFails, ' times in timestep ', myIter+1
409 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
410 & SQUEEZE_RIGHT, myThid )
411 _END_MASTER( myThid )
412 ENDIF
413 _BEGIN_MASTER( myThid )
414 WRITE(msgBuf,'(A,I6,A,I10)')
415 & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
416 & totalKrylovItersLoc, ' in timestep ', myIter+1
417 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
418 & SQUEEZE_RIGHT, myThid )
419 _END_MASTER( myThid )
420 ENDIF
421
422 RETURN
423 END
424
425 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
426 CBOP
427 C !ROUTINE: SEAICE_JFNK_UPDATE
428 C !INTERFACE:
429
430 SUBROUTINE SEAICE_JFNK_UPDATE(
431 I duIce, dvIce,
432 U uIce, vIce, JFNKresidual,
433 O uIceRes, vIceRes,
434 I newtonIter, myTime, myIter, myThid )
435
436 C !DESCRIPTION: \bv
437 C *==========================================================*
438 C | SUBROUTINE SEAICE_JFNK_UPDATE
439 C | o Update velocities with incremental solutions of FGMRES
440 C | o compute residual of updated solutions and do
441 C | o linesearch:
442 C | reduce update until residual is smaller than previous
443 C | one (input)
444 C *==========================================================*
445 C | written by Martin Losch, Jan 2013
446 C *==========================================================*
447 C \ev
448
449 C !USES:
450 IMPLICIT NONE
451
452 C === Global variables ===
453 #include "SIZE.h"
454 #include "EEPARAMS.h"
455 #include "PARAMS.h"
456 #include "SEAICE_SIZE.h"
457 #include "SEAICE_PARAMS.h"
458
459 C !INPUT/OUTPUT PARAMETERS:
460 C === Routine arguments ===
461 C myTime :: Simulation time
462 C myIter :: Simulation timestep number
463 C myThid :: my Thread Id. number
464 C newtonIter :: current iterate of Newton iteration
465 _RL myTime
466 INTEGER myIter
467 INTEGER myThid
468 INTEGER newtonIter
469 C JFNKresidual :: Residual at the beginning of the FGMRES iteration,
470 C changes with newtonIter (updated)
471 _RL JFNKresidual
472 C du/vIce :: ice velocity increment to be added to u/vIce (input)
473 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
474 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
475 C u/vIce :: ice velocity increment to be added to u/vIce (updated)
476 _RL uIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
477 _RL vIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
478 C u/vIceRes :: residual of sea-ice momentum equations (output)
479 _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
480 _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
481
482 C !LOCAL VARIABLES:
483 C === Local variables ===
484 C i,j,bi,bj :: loop indices
485 INTEGER i,j,bi,bj
486 INTEGER l
487 _RL resLoc, facLS
488 LOGICAL doLineSearch
489 C nVec :: size of the input vector(s)
490 C resTmp :: vector version of the residuals
491 INTEGER nVec
492 PARAMETER ( nVec = 2*sNx*sNy )
493 _RL resTmp (nVec,1,nSx,nSy)
494
495 CHARACTER*(MAX_LEN_MBUF) msgBuf
496 CEOP
497
498 C Initialise some local variables
499 l = 0
500 resLoc = JFNKresidual
501 facLS = 1. _d 0
502 doLineSearch = .TRUE.
503 DO WHILE ( doLineSearch )
504 C Create update
505 DO bj=myByLo(myThid),myByHi(myThid)
506 DO bi=myBxLo(myThid),myBxHi(myThid)
507 DO J=1-OLy,sNy+OLy
508 DO I=1-OLx,sNx+OLx
509 uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
510 vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
511 ENDDO
512 ENDDO
513 ENDDO
514 ENDDO
515 C Compute current residual F(u), (includes re-computation of global
516 C variables DWATN, zeta, and eta, i.e. they are different after this)
517 CALL SEAICE_CALC_RESIDUAL(
518 I uIce, vIce,
519 O uIceRes, vIceRes,
520 I newtonIter, 0, myTime, myIter, myThid )
521 C Important: Compute the norm of the residual using the same scalar
522 C product that SEAICE_FGMRES does
523 CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
524 CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
525 resLoc = SQRT(resLoc)
526 C Determine, if we need more iterations
527 doLineSearch = resLoc .GE. JFNKresidual
528 C Limit the maximum number of iterations arbitrarily to four
529 doLineSearch = doLineSearch .AND. l .LT. 4
530 C For the first iteration du/vIce = 0 and there will be no
531 C improvement of the residual possible, so we do only the first
532 C iteration
533 IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
534 C Only start a linesearch after some Newton iterations
535 IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
536 C Increment counter
537 l = l + 1
538 C some output diagnostics
539 IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
540 _BEGIN_MASTER( myThid )
541 WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
542 & ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
543 & 'facLS, JFNKresidual, resLoc = ',
544 & newtonIter, l, facLS, JFNKresidual, resLoc
545 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
546 & SQUEEZE_RIGHT, myThid )
547 _END_MASTER( myThid )
548 ENDIF
549 C Get ready for the next iteration: after adding du/vIce in the first
550 C iteration, we substract 0.5*du/vIce from u/vIce in the next
551 C iterations, 0.25*du/vIce in the second, etc.
552 facLS = - 0.5 _d 0 * ABS(facLS)
553 ENDDO
554 C This is the new residual
555 JFNKresidual = resLoc
556
557 #endif /* SEAICE_ALLOW_JFNK */
558
559 RETURN
560 END

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