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Revision 1.15 - (show annotations) (download)
Wed Jan 16 21:20:28 2013 UTC (12 years, 6 months ago) by mlosch
Branch: MAIN
Changes since 1.14: +183 -19 lines
add a line search option to the JFNK solver

1 C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_jfnk.F,v 1.14 2013/01/04 15:48:09 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 #if ( (defined SEAICE_CGRID) && \
57 (defined SEAICE_ALLOW_JFNK) && \
58 (defined SEAICE_ALLOW_DYNAMICS) )
59 C !FUNCTIONS:
60 LOGICAL DIFFERENT_MULTIPLE
61 EXTERNAL DIFFERENT_MULTIPLE
62
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 phi_e, alp_e, JFNKgamma_lin
77 _RL FGMRESeps
78 _RL JFNKtol
79 C
80 _RL recip_deltaT
81 LOGICAL JFNKconverged, krylovConverged
82 LOGICAL writeNow
83 CHARACTER*(MAX_LEN_MBUF) msgBuf
84 C
85 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 vector version of the residuals
89 _RL resTmp (nVec,1,nSx,nSy)
90 C du/vIce :: ice velocity increment to be added to u/vIce
91 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
92 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
93 C precomputed (= constant per Newton iteration) versions of
94 C zeta, eta, and DWATN, press
95 _RL zetaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
96 _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
97 _RL etaZPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
98 _RL dwatPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
99 CEOP
100
101 C Initialise
102 newtonIter = 0
103 krylovFails = 0
104 totalKrylovItersLoc = 0
105 JFNKconverged = .FALSE.
106 JFNKtol = 0. _d 0
107 JFNKresidual = 0. _d 0
108 JFNKresidualKm1 = 0. _d 0
109 FGMRESeps = 0. _d 0
110 recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
111
112 iOutFGMRES=0
113 C with iOutFgmres=1, seaice_fgmres prints the residual at each iteration
114 IF ( debugLevel.GE.debLevC .AND.
115 & DIFFERENT_MULTIPLE( SEAICE_monFreq, myTime, deltaTClock ) )
116 & iOutFGMRES=1
117
118 C
119 DO bj=myByLo(myThid),myByHi(myThid)
120 DO bi=myBxLo(myThid),myBxHi(myThid)
121 DO J=1-Oly,sNy+Oly
122 DO I=1-Olx,sNx+Olx
123 uIceRes(I,J,bi,bj) = 0. _d 0
124 vIceRes(I,J,bi,bj) = 0. _d 0
125 duIce (I,J,bi,bj) = 0. _d 0
126 dvIce (I,J,bi,bj) = 0. _d 0
127 uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
128 vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
129 ENDDO
130 ENDDO
131 C Compute things that do no change during the Newton iteration:
132 C sea-surface tilt and wind stress:
133 C FORCEX/Y0 - mass*(u/vIceNm1)/deltaT
134 DO J=1-Oly,sNy+Oly
135 DO I=1-Olx,sNx+Olx
136 FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
137 & + seaiceMassU(I,J,bi,bj)*uIceNm1(I,J,bi,bj)*recip_deltaT
138 FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
139 & + seaiceMassV(I,J,bi,bj)*vIceNm1(I,J,bi,bj)*recip_deltaT
140 ENDDO
141 ENDDO
142 ENDDO
143 ENDDO
144 C Start nonlinear Newton iteration: outer loop iteration
145 DO WHILE ( newtonIter.LT.SEAICEnewtonIterMax .AND.
146 & .NOT.JFNKconverged )
147 newtonIter = newtonIter + 1
148 C Compute initial residual F(u), (includes computation of global
149 C variables DWATN, zeta, and eta)
150 C Update linear solution vector and return to Newton iteration
151 C Do the linesearch
152 CALL SEAICE_JFNK_UPDATE(
153 I duIce, dvIce,
154 U uIce, vIce, JFNKresidual,
155 O uIceRes, vIceRes,
156 I newtonIter, myTime, myIter, myThid )
157 C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
158 DO bj=myByLo(myThid),myByHi(myThid)
159 DO bi=myBxLo(myThid),myBxHi(myThid)
160 DO J=1-Oly,sNy+Oly
161 DO I=1-Olx,sNx+Olx
162 duIce(I,J,bi,bj)= 0. _d 0
163 dvIce(I,J,bi,bj)= 0. _d 0
164 ENDDO
165 ENDDO
166 ENDDO
167 ENDDO
168 CMLC Do it again, Sam
169 CML CALL SEAICE_CALC_RESIDUAL(
170 CML I uIce, vIce,
171 CML O uIceRes, vIceRes,
172 CML I newtonIter, 0, myTime, myIter, myThid )
173 CMLC probably not necessary, will be removed later:
174 CML CALL EXCH_UV_XY_RL( uIceRes, vIceRes,.TRUE.,myThid)
175 CMLC Important: Compute the norm of the residual using the same scalar
176 CMLC product that SEAICE_FGMRES does
177 CML CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
178 CML CALL SEAICE_SCALPROD(
179 CML & nVec,1,1,1,resTmp,resTmp,JFNKresidual,myThid)
180 CML JFNKresidual = SQRT(JFNKresidual)
181 C local copies of precomputed coefficients that are to stay
182 C constant for the preconditioner
183 DO bj=myByLo(myThid),myByHi(myThid)
184 DO bi=myBxLo(myThid),myBxHi(myThid)
185 DO j=1-Oly,sNy+Oly
186 DO i=1-Olx,sNx+Olx
187 zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
188 etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
189 etaZPre(I,J,bi,bj) = etaZ(I,J,bi,bj)
190 dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
191 ENDDO
192 ENDDO
193 ENDDO
194 ENDDO
195 C compute convergence criterion for linear preconditioned FGMRES
196 JFNKgamma_lin = JFNKgamma_lin_max
197 IF ( newtonIter.GT.1.AND.newtonIter.LE.100
198 & .AND.JFNKresidual.LT.JFNKres_t ) THEN
199 C Eisenstat, 1996, equ.(2.6)
200 phi_e = 1. _d 0
201 alp_e = 1. _d 0
202 JFNKgamma_lin = phi_e*( JFNKresidual/JFNKresidualKm1 )**alp_e
203 JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
204 JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
205 ENDIF
206 C save the residual for the next iteration
207 JFNKresidualKm1 = JFNKresidual
208 C
209 C The Krylov iteration using FGMRES, the preconditioner is LSOR
210 C for now. The code is adapted from SEAICE_LSR, but heavily stripped
211 C down.
212 C krylovIter is mapped into "its" in seaice_fgmres and is incremented
213 C in that routine
214 krylovIter = 0
215 iCode = 0
216 C
217 JFNKconverged = JFNKresidual.LT.JFNKtol
218 C
219 C do Krylov loop only if convergence is not reached
220 C
221 IF ( .NOT.JFNKconverged ) THEN
222 C
223 C start Krylov iteration (FGMRES)
224 C
225 krylovConverged = .FALSE.
226 FGMRESeps = JFNKgamma_lin * JFNKresidual
227 DO WHILE ( .NOT.krylovConverged )
228 C solution vector sol = du/vIce
229 C residual vector (rhs) Fu = u/vIceRes
230 C output work vectors wk1, -> input work vector wk2
231 C
232 CALL SEAICE_FGMRES_DRIVER(
233 I uIceRes, vIceRes,
234 U duIce, dvIce, iCode,
235 I FGMRESeps, iOutFGMRES,
236 I newtonIter, krylovIter, myTime, myIter, myThid )
237 C FGMRES returns iCode either asking for an new preconditioned vector
238 C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
239 C iteration
240 IF (iCode.EQ.1) THEN
241 C Call preconditioner
242 IF ( SOLV_MAX_ITERS .GT. 0 )
243 & CALL SEAICE_PRECONDITIONER(
244 U duIce, dvIce,
245 I zetaPre, etaPre, etaZpre, dwatPre,
246 I newtonIter, krylovIter, myTime, myIter, myThid )
247 ELSEIF (iCode.GE.2) THEN
248 C Compute Jacobian times vector
249 CALL SEAICE_JACVEC(
250 I uIce, vIce, uIceRes, vIceRes,
251 U duIce, dvIce,
252 I newtonIter, krylovIter, myTime, myIter, myThid )
253 ENDIF
254 krylovConverged = iCode.EQ.0
255 C End of Krylov iterate
256 ENDDO
257 totalKrylovItersLoc = totalKrylovItersLoc + krylovIter
258 C some output diagnostics
259 IF ( debugLevel.GE.debLevA ) THEN
260 _BEGIN_MASTER( myThid )
261 totalNewtonItersLoc =
262 & SEAICEnewtonIterMax*(myIter-nIter0)+newtonIter
263 WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
264 & ' S/R SEAICE_JFNK: Newton iterate / total, ',
265 & 'JFNKgamma_lin, initial norm = ',
266 & newtonIter, totalNewtonItersLoc,
267 & JFNKgamma_lin,JFNKresidual
268 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
269 & SQUEEZE_RIGHT, myThid )
270 WRITE(msgBuf,'(3(A,I6))')
271 & ' S/R SEAICE_JFNK: Newton iterate / total = ',newtonIter,
272 & ' / ', totalNewtonItersLoc,
273 & ', Nb. of FGMRES iterations = ', krylovIter
274 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
275 & SQUEEZE_RIGHT, myThid )
276 _END_MASTER( myThid )
277 ENDIF
278 IF ( krylovIter.EQ.SEAICEkrylovIterMax ) THEN
279 krylovFails = krylovFails + 1
280 ENDIF
281 C Set the stopping criterion for the Newton iteration
282 IF ( newtonIter .EQ. 1 ) JFNKtol=JFNKgamma_nonlin*JFNKresidual
283 C Update linear solution vector and return to Newton iteration
284 C Do a linesearch if necessary, and compute a new residual.
285 C Note that it should be possible to do the following operations
286 C at the beginning of the Newton iteration, thereby saving us from
287 C the extra call of seaice_jfnk_update, but unfortunately that
288 C changes the results, so we leave the stuff here for now.
289 CALL SEAICE_JFNK_UPDATE(
290 I duIce, dvIce,
291 U uIce, vIce, JFNKresidual,
292 O uIceRes, vIceRes,
293 I newtonIter, myTime, myIter, myThid )
294 C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
295 DO bj=myByLo(myThid),myByHi(myThid)
296 DO bi=myBxLo(myThid),myBxHi(myThid)
297 DO J=1-Oly,sNy+Oly
298 DO I=1-Olx,sNx+Olx
299 duIce(I,J,bi,bj)= 0. _d 0
300 dvIce(I,J,bi,bj)= 0. _d 0
301 ENDDO
302 ENDDO
303 ENDDO
304 ENDDO
305 ENDIF
306 C end of Newton iterate
307 ENDDO
308 C
309 C-- Output diagnostics
310 C
311 IF ( SEAICE_monFreq .GT. 0. _d 0 ) THEN
312 C Count iterations
313 totalJFNKtimeSteps = totalJFNKtimeSteps + 1
314 totalNewtonIters = totalNewtonIters + newtonIter
315 totalKrylovIters = totalKrylovIters + totalKrylovItersLoc
316 C Record failure
317 totalKrylovFails = totalKrylovFails + krylovFails
318 IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
319 totalNewtonFails = totalNewtonFails + 1
320 ENDIF
321 ENDIF
322 C Decide whether it is time to dump and reset the counter
323 writeNow = DIFFERENT_MULTIPLE(SEAICE_monFreq,
324 & myTime+deltaTClock, deltaTClock)
325 #ifdef ALLOW_CAL
326 IF ( useCAL ) THEN
327 CALL CAL_TIME2DUMP(
328 I zeroRL, SEAICE_monFreq, deltaTClock,
329 U writeNow,
330 I myTime+deltaTclock, myIter+1, myThid )
331 ENDIF
332 #endif
333 IF ( writeNow ) THEN
334 _BEGIN_MASTER( myThid )
335 WRITE(msgBuf,'(A)')
336 &' // ======================================================='
337 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
338 & SQUEEZE_RIGHT, myThid )
339 WRITE(msgBuf,'(A)') ' // Begin JFNK statistics'
340 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
341 & SQUEEZE_RIGHT, myThid )
342 WRITE(msgBuf,'(A)')
343 &' // ======================================================='
344 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
345 & SQUEEZE_RIGHT, myThid )
346 WRITE(msgBuf,'(A,I10)')
347 & ' %JFNK_MON: time step = ', myIter+1
348 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
349 & SQUEEZE_RIGHT, myThid )
350 WRITE(msgBuf,'(A,I10)')
351 & ' %JFNK_MON: Nb. of time steps = ', totalJFNKtimeSteps
352 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
353 & SQUEEZE_RIGHT, myThid )
354 WRITE(msgBuf,'(A,I10)')
355 & ' %JFNK_MON: Nb. of Newton steps = ', totalNewtonIters
356 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
357 & SQUEEZE_RIGHT, myThid )
358 WRITE(msgBuf,'(A,I10)')
359 & ' %JFNK_MON: Nb. of Krylov steps = ', totalKrylovIters
360 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
361 & SQUEEZE_RIGHT, myThid )
362 WRITE(msgBuf,'(A,I10)')
363 & ' %JFNK_MON: Nb. of Newton failures = ', totalNewtonFails
364 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
365 & SQUEEZE_RIGHT, myThid )
366 WRITE(msgBuf,'(A,I10)')
367 & ' %JFNK_MON: Nb. of Krylov failures = ', totalKrylovFails
368 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
369 & SQUEEZE_RIGHT, myThid )
370 WRITE(msgBuf,'(A)')
371 &' // ======================================================='
372 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
373 & SQUEEZE_RIGHT, myThid )
374 WRITE(msgBuf,'(A)') ' // End JFNK statistics'
375 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
376 & SQUEEZE_RIGHT, myThid )
377 WRITE(msgBuf,'(A)')
378 &' // ======================================================='
379 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
380 & SQUEEZE_RIGHT, myThid )
381 _END_MASTER( myThid )
382 C reset and start again
383 totalJFNKtimeSteps = 0
384 totalNewtonIters = 0
385 totalKrylovIters = 0
386 totalKrylovFails = 0
387 totalNewtonFails = 0
388 ENDIF
389
390 C Print more debugging information
391 IF ( debugLevel.GE.debLevA ) THEN
392 IF ( newtonIter .EQ. SEAICEnewtonIterMax ) THEN
393 _BEGIN_MASTER( myThid )
394 WRITE(msgBuf,'(A,I10)')
395 & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
396 & myIter+1
397 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
398 & SQUEEZE_RIGHT, myThid )
399 _END_MASTER( myThid )
400 ENDIF
401 IF ( krylovFails .GT. 0 ) THEN
402 _BEGIN_MASTER( myThid )
403 WRITE(msgBuf,'(A,I4,A,I10)')
404 & ' S/R SEAICE_JFNK: FGMRES did not converge ',
405 & krylovFails, ' times in timestep ', myIter+1
406 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
407 & SQUEEZE_RIGHT, myThid )
408 _END_MASTER( myThid )
409 ENDIF
410 _BEGIN_MASTER( myThid )
411 WRITE(msgBuf,'(A,I6,A,I10)')
412 & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
413 & totalKrylovItersLoc, ' in timestep ', myIter+1
414 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
415 & SQUEEZE_RIGHT, myThid )
416 _END_MASTER( myThid )
417 ENDIF
418
419 RETURN
420 END
421
422 CBOP
423 C !ROUTINE: SEAICE_JFNK_UPDATE
424 C !INTERFACE:
425
426 SUBROUTINE SEAICE_JFNK_UPDATE(
427 I duIce, dvIce,
428 U uIce, vIce, JFNKresidual,
429 O uIceRes, vIceRes,
430 I newtonIter, myTime, myIter, myThid )
431
432 C !DESCRIPTION: \bv
433 C *==========================================================*
434 C | SUBROUTINE SEAICE_JFNK_UPDATE
435 C | o Update velocities with incremental solutions of FGMRES
436 C | o compute residual of updated solutions and do
437 C | o linesearch:
438 C | reduce update until residual is smaller than previous
439 C | one (input)
440 C *==========================================================*
441 C | written by Martin Losch, Jan 2013
442 C *==========================================================*
443 C \ev
444
445 C !USES:
446 IMPLICIT NONE
447
448 C === Global variables ===
449 #include "SIZE.h"
450 #include "EEPARAMS.h"
451 #include "PARAMS.h"
452 #include "SEAICE_SIZE.h"
453 #include "SEAICE_PARAMS.h"
454
455 C !INPUT/OUTPUT PARAMETERS:
456 C === Routine arguments ===
457 C myTime :: Simulation time
458 C myIter :: Simulation timestep number
459 C myThid :: my Thread Id. number
460 C newtonIter :: current iterate of Newton iteration
461 _RL myTime
462 INTEGER myIter
463 INTEGER myThid
464 INTEGER newtonIter
465 C JFNKresidual :: Residual at the beginning of the FGMRES iteration,
466 C changes with newtonIter (updated)
467 _RL JFNKresidual
468 C du/vIce :: ice velocity increment to be added to u/vIce (input)
469 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
470 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
471 C u/vIce :: ice velocity increment to be added to u/vIce (updated)
472 _RL uIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
473 _RL vIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
474 C u/vIceRes :: residual of sea-ice momentum equations (output)
475 _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
476 _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
477
478 C Local variables:
479 C i,j,bi,bj :: loop indices
480 INTEGER i,j,bi,bj
481 INTEGER l
482 _RL resLoc, facLS
483 LOGICAL doLineSearch
484 C nVec :: size of the input vector(s)
485 C vector version of the residuals
486 INTEGER nVec
487 PARAMETER ( nVec = 2*sNx*sNy )
488 _RL resTmp (nVec,1,nSx,nSy)
489 C
490 CHARACTER*(MAX_LEN_MBUF) msgBuf
491 CEOP
492
493 C Initialise some local variables
494 l = 0
495 resLoc = JFNKresidual
496 facLS = 1. _d 0
497 doLineSearch = .TRUE.
498 DO WHILE ( doLineSearch )
499 C Determine, if we need more iterations
500 doLineSearch = resLoc .GE. JFNKresidual
501 doLineSearch = doLineSearch .AND. l .LE. 4
502 C For the first iteration du/vIce = 0 and there will be no
503 C improvement of the residual possible, so we do only the first
504 C iteration
505 IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
506 C Only start a linesearch after some Newton iterations
507 IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
508 C Increment counter
509 l = l + 1
510 C Create update
511 DO bj=myByLo(myThid),myByHi(myThid)
512 DO bi=myBxLo(myThid),myBxHi(myThid)
513 DO J=1-Oly,sNy+Oly
514 DO I=1-Olx,sNx+Olx
515 uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
516 vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
517 ENDDO
518 ENDDO
519 ENDDO
520 ENDDO
521 C Compute current residual F(u), (includes re-computation of global
522 C variables DWATN, zeta, and eta, i.e. they are different after this)
523 CALL SEAICE_CALC_RESIDUAL(
524 I uIce, vIce,
525 O uIceRes, vIceRes,
526 I newtonIter, 0, myTime, myIter, myThid )
527 C Important: Compute the norm of the residual using the same scalar
528 C product that SEAICE_FGMRES does
529 CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
530 CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
531 resLoc = SQRT(resLoc)
532 C some output diagnostics
533 IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
534 _BEGIN_MASTER( myThid )
535 WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
536 & ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
537 & 'facLS, JFNKresidual, resLoc = ',
538 & newtonIter, l, facLS, JFNKresidual, resLoc
539 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
540 & SQUEEZE_RIGHT, myThid )
541 _END_MASTER( myThid )
542 ENDIF
543 C Get ready for the next iteration: after adding du/vIce in the first
544 C iteration, we substract 0.5*du/vIce from u/vIce in the next
545 C iterations, 0.25*du/vIce in the second, etc.
546 facLS = - 0.5 _d 0 * ABS(facLS)
547 ENDDO
548 C This is the new residual
549 JFNKresidual = resLoc
550
551 #endif /* SEAICE_ALLOW_DYNAMICS and SEAICE_CGRID and SEAICE_ALLOW_JFNK */
552
553 RETURN
554 END

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