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Revision 1.31 - (show annotations) (download)
Thu Jun 8 15:33:50 2017 UTC (8 years, 1 month ago) by mlosch
Branch: MAIN
CVS Tags: checkpoint66o, checkpoint66n, checkpoint66m, checkpoint66l, checkpoint66k, checkpoint66j, checkpoint66i, HEAD
Changes since 1.30: +2 -1 lines
Error occurred while calculating annotation data.
prevent JFNK and KRYLOV solvers from trying to reduce a residual of 0

1 C $Header: /u/gcmpack/MITgcm/pkg/seaice/seaice_jfnk.F,v 1.30 2016/01/28 12:54:12 mlosch Exp $
2 C $Name: $
3
4 #include "SEAICE_OPTIONS.h"
5 #ifdef ALLOW_AUTODIFF
6 # include "AUTODIFF_OPTIONS.h"
7 #endif
8
9 C-- File seaice_jfnk.F: seaice jfnk dynamical solver S/R:
10 C-- Contents
11 C-- o SEAICE_JFNK
12 C-- o SEAICE_JFNK_UPDATE
13
14 CBOP
15 C !ROUTINE: SEAICE_JFNK
16 C !INTERFACE:
17 SUBROUTINE SEAICE_JFNK( myTime, myIter, myThid )
18
19 C !DESCRIPTION: \bv
20 C *==========================================================*
21 C | SUBROUTINE SEAICE_JFNK
22 C | o Ice dynamics using a Jacobian-free Newton-Krylov solver
23 C | following J.-F. Lemieux et al. Improving the numerical
24 C | convergence of viscous-plastic sea ice models with the
25 C | Jacobian-free Newton-Krylov method. J. Comp. Phys. 229,
26 C | 2840-2852 (2010).
27 C | o The logic follows JFs code.
28 C *==========================================================*
29 C | written by Martin Losch, Oct 2012
30 C *==========================================================*
31 C \ev
32
33 C !USES:
34 IMPLICIT NONE
35
36 C === Global variables ===
37 #include "SIZE.h"
38 #include "EEPARAMS.h"
39 #include "PARAMS.h"
40 #include "DYNVARS.h"
41 #include "GRID.h"
42 #include "SEAICE_SIZE.h"
43 #include "SEAICE_PARAMS.h"
44 #include "SEAICE.h"
45
46 #ifdef ALLOW_AUTODIFF_TAMC
47 # include "tamc.h"
48 #endif
49
50 C !INPUT/OUTPUT PARAMETERS:
51 C === Routine arguments ===
52 C myTime :: Simulation time
53 C myIter :: Simulation timestep number
54 C myThid :: my Thread Id. number
55 _RL myTime
56 INTEGER myIter
57 INTEGER myThid
58
59 #ifdef SEAICE_ALLOW_JFNK
60 C !FUNCTIONS:
61 LOGICAL DIFFERENT_MULTIPLE
62 EXTERNAL DIFFERENT_MULTIPLE
63
64 C !LOCAL VARIABLES:
65 C === Local variables ===
66 C i,j,bi,bj :: loop indices
67 INTEGER i,j,bi,bj
68 C loop indices
69 INTEGER newtonIter
70 INTEGER krylovIter, krylovFails
71 INTEGER totalKrylovItersLoc, totalNewtonItersLoc
72 C FGMRES parameters
73 C im :: size of Krylov space
74 C ifgmres :: interation counter
75 INTEGER im
76 PARAMETER ( im = 50 )
77 INTEGER ifgmres
78 C FGMRES flag that determines amount of output messages of fgmres
79 INTEGER iOutFGMRES
80 C FGMRES flag that indicates what fgmres wants us to do next
81 INTEGER iCode
82 _RL JFNKresidual
83 _RL JFNKresidualKm1
84 C parameters to compute convergence criterion
85 _RL JFNKgamma_lin
86 _RL FGMRESeps
87 _RL JFNKtol
88 C backward differences extrapolation factors
89 _RL bdfFac, bdfAlpha
90 C
91 _RL recip_deltaT
92 LOGICAL JFNKconverged, krylovConverged
93 LOGICAL writeNow
94 CHARACTER*(MAX_LEN_MBUF) msgBuf
95
96 C u/vIceRes :: residual of sea-ice momentum equations
97 _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
98 _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
99 C extra time level required for backward difference time stepping
100 _RL duIcNm1(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
101 _RL dvIcNm1(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
102 C du/vIce :: ice velocity increment to be added to u/vIce
103 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
104 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
105 C precomputed (= constant per Newton iteration) versions of
106 C zeta, eta, and DWATN, press
107 _RL zetaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
108 _RL zetaZPre(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
109 _RL etaPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
110 _RL etaZPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
111 _RL dwatPre (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
112 C work arrays
113 _RL rhs(nVec,nSx,nSy), sol(nVec,nSx,nSy)
114 _RL vv(nVec,im+1,nSx,nSy), w(nVec,im,nSx,nSy)
115 _RL wk1(nVec,nSx,nSy), wk2(nVec,nSx,nSy)
116 CEOP
117
118 C Initialise
119 newtonIter = 0
120 krylovFails = 0
121 totalKrylovItersLoc = 0
122 JFNKconverged = .FALSE.
123 JFNKtol = 0. _d 0
124 JFNKresidual = 0. _d 0
125 JFNKresidualKm1 = 0. _d 0
126 FGMRESeps = 0. _d 0
127 recip_deltaT = 1. _d 0 / SEAICE_deltaTdyn
128
129 iOutFGMRES=0
130 C with iOutFgmres=1, seaice_fgmres prints the residual at each iteration
131 IF ( debugLevel.GE.debLevC .AND.
132 & DIFFERENT_MULTIPLE( SEAICE_monFreq, myTime, deltaTClock ) )
133 & iOutFGMRES=1
134
135 C backward difference extrapolation factors
136 bdfFac = 0. _d 0
137 IF ( SEAICEuseBDF2 ) THEN
138 IF ( myIter.EQ.nIter0 .AND. SEAICEmomStartBDF.EQ.0 ) THEN
139 bdfFac = 0. _d 0
140 ELSE
141 bdfFac = 0.5 _d 0
142 ENDIF
143 ENDIF
144 bdfAlpha = 1. _d 0 + bdfFac
145
146 DO bj=myByLo(myThid),myByHi(myThid)
147 DO bi=myBxLo(myThid),myBxHi(myThid)
148 DO J=1-OLy,sNy+OLy
149 DO I=1-OLx,sNx+OLx
150 uIceRes(I,J,bi,bj) = 0. _d 0
151 vIceRes(I,J,bi,bj) = 0. _d 0
152 duIce (I,J,bi,bj) = 0. _d 0
153 dvIce (I,J,bi,bj) = 0. _d 0
154 ENDDO
155 ENDDO
156 C cycle ice velocities
157 DO J=1-OLy,sNy+OLy
158 DO I=1-OLx,sNx+OLx
159 duIcNm1(I,J,bi,bj) = uIce(I,J,bi,bj) * bdfAlpha
160 & + ( uIce(I,J,bi,bj) - uIceNm1(I,J,bi,bj) ) * bdfFac
161 dvIcNm1(I,J,bi,bj) = vIce(I,J,bi,bj) * bdfAlpha
162 & + ( vIce(I,J,bi,bj) - vIceNm1(I,J,bi,bj) ) * bdfFac
163 uIceNm1(I,J,bi,bj) = uIce(I,J,bi,bj)
164 vIceNm1(I,J,bi,bj) = vIce(I,J,bi,bj)
165 ENDDO
166 ENDDO
167 C As long as IMEX is not properly implemented leave this commented out
168 CML IF ( .NOT.SEAICEuseIMEX ) THEN
169 C Compute things that do no change during the Newton iteration:
170 C sea-surface tilt and wind stress:
171 C FORCEX/Y0 - mass*(1.5*u/vIceNm1+0.5*(u/vIceNm1-u/vIceNm2))/deltaT
172 DO J=1-OLy,sNy+OLy
173 DO I=1-OLx,sNx+OLx
174 FORCEX(I,J,bi,bj) = FORCEX0(I,J,bi,bj)
175 & + seaiceMassU(I,J,bi,bj)*duIcNm1(I,J,bi,bj)*recip_deltaT
176 FORCEY(I,J,bi,bj) = FORCEY0(I,J,bi,bj)
177 & + seaiceMassV(I,J,bi,bj)*dvIcNm1(I,J,bi,bj)*recip_deltaT
178 ENDDO
179 ENDDO
180 CML ENDIF
181 ENDDO
182 ENDDO
183 C Start nonlinear Newton iteration: outer loop iteration
184 DO WHILE ( newtonIter.LT.SEAICEnonLinIterMax .AND.
185 & .NOT.JFNKconverged )
186 newtonIter = newtonIter + 1
187 C Compute initial residual F(u), (includes computation of global
188 C variables DWATN, zeta, and eta)
189 IF ( newtonIter .EQ. 1 ) CALL SEAICE_JFNK_UPDATE(
190 I duIce, dvIce,
191 U uIce, vIce, JFNKresidual,
192 O uIceRes, vIceRes,
193 I newtonIter, myTime, myIter, myThid )
194 C local copies of precomputed coefficients that are to stay
195 C constant for the preconditioner
196 DO bj=myByLo(myThid),myByHi(myThid)
197 DO bi=myBxLo(myThid),myBxHi(myThid)
198 DO j=1-OLy,sNy+OLy
199 DO i=1-OLx,sNx+OLx
200 zetaPre(I,J,bi,bj) = zeta(I,J,bi,bj)
201 zetaZPre(I,J,bi,bj)= zetaZ(I,J,bi,bj)
202 etaPre(I,J,bi,bj) = eta(I,J,bi,bj)
203 etaZPre(I,J,bi,bj) = etaZ(I,J,bi,bj)
204 dwatPre(I,J,bi,bj) = DWATN(I,J,bi,bj)
205 ENDDO
206 ENDDO
207 ENDDO
208 ENDDO
209 C compute convergence criterion for linear preconditioned FGMRES
210 JFNKgamma_lin = JFNKgamma_lin_max
211 IF ( newtonIter.GT.1.AND.newtonIter.LE.SEAICE_JFNK_tolIter
212 & .AND.JFNKresidual.LT.JFNKres_t ) THEN
213 C Eisenstat and Walker (1996), eq.(2.6)
214 JFNKgamma_lin = SEAICE_JFNKphi
215 & *( JFNKresidual/JFNKresidualKm1 )**SEAICE_JFNKalpha
216 JFNKgamma_lin = min(JFNKgamma_lin_max, JFNKgamma_lin)
217 JFNKgamma_lin = max(JFNKgamma_lin_min, JFNKgamma_lin)
218 ENDIF
219 C save the residual for the next iteration
220 JFNKresidualKm1 = JFNKresidual
221
222 C The Krylov iteration using FGMRES, the preconditioner is LSOR
223 C for now. The code is adapted from SEAICE_LSR, but heavily stripped
224 C down.
225 C krylovIter is mapped into "its" in seaice_fgmres and is incremented
226 C in that routine
227 krylovIter = 0
228 iCode = 0
229
230 JFNKconverged = JFNKresidual.LT.JFNKtol
231 & .OR.JFNKresidual.EQ.0. _d 0
232
233 C do Krylov loop only if convergence is not reached
234
235 IF ( .NOT.JFNKconverged ) THEN
236
237 C start Krylov iteration (FGMRES)
238
239 krylovConverged = .FALSE.
240 FGMRESeps = JFNKgamma_lin * JFNKresidual
241 C map first guess sol; it is zero because the solution is a correction
242 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,sol,.TRUE.,myThid)
243 C map rhs and change its sign because we are solving J*u = -F
244 CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,rhs,.TRUE.,myThid)
245 DO bj=myByLo(myThid),myByHi(myThid)
246 DO bi=myBxLo(myThid),myBxHi(myThid)
247 DO j=1,nVec
248 rhs(j,bi,bj) = - rhs(j,bi,bj)
249 ENDDO
250 ENDDO
251 ENDDO
252 DO WHILE ( .NOT.krylovConverged )
253 C solution vector sol = du/vIce
254 C residual vector (rhs) Fu = u/vIceRes
255 C output work vectors wk1, -> input work vector wk2
256
257 C map preconditioner results or Jacobian times vector,
258 C stored in du/vIce to wk2, for iCode=0, wk2 is set to zero,
259 C because du/vIce = 0
260 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,wk2,.TRUE.,myThid)
261 C
262 CALL SEAICE_FGMRES (nVec,im,rhs,sol,ifgmres,krylovIter,
263 U vv,w,wk1,wk2,
264 I FGMRESeps,SEAICElinearIterMax,iOutFGMRES,
265 U iCode,
266 I myThid)
267 C
268 IF ( iCode .EQ. 0 ) THEN
269 C map sol(ution) vector to du/vIce
270 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,sol,.FALSE.,myThid)
271 ELSE
272 C map work vector to du/vIce to either compute a preconditioner
273 C solution (wk1=rhs) or a Jacobian times wk1
274 CALL SEAICE_MAP2VEC(nVec,duIce,dvIce,wk1,.FALSE.,myThid)
275 ENDIF
276 C Fill overlaps in updated fields
277 CALL EXCH_UV_XY_RL( duIce, dvIce,.TRUE.,myThid)
278 C FGMRES returns iCode either asking for an new preconditioned vector
279 C or product of matrix (Jacobian) times vector. For iCode = 0, terminate
280 C iteration
281 IF (iCode.EQ.1) THEN
282 C Call preconditioner
283 IF ( SEAICEpreconLinIter .GT. 0 )
284 & CALL SEAICE_PRECONDITIONER(
285 U duIce, dvIce,
286 I zetaPre, etaPre, etaZpre, zetaZpre, dwatPre,
287 I newtonIter, krylovIter, myTime, myIter, myThid )
288 ELSEIF (iCode.GE.2) THEN
289 C Compute Jacobian times vector
290 CALL SEAICE_JACVEC(
291 I uIce, vIce, uIceRes, vIceRes,
292 U duIce, dvIce,
293 I newtonIter, krylovIter, myTime, myIter, myThid )
294 ENDIF
295 krylovConverged = iCode.EQ.0
296 C End of Krylov iterate
297 ENDDO
298 totalKrylovItersLoc = totalKrylovItersLoc + krylovIter
299 C some output diagnostics
300 IF ( debugLevel.GE.debLevA ) THEN
301 _BEGIN_MASTER( myThid )
302 totalNewtonItersLoc =
303 & SEAICEnonLinIterMax*(myIter-nIter0)+newtonIter
304 WRITE(msgBuf,'(2A,2(1XI6),2E12.5)')
305 & ' S/R SEAICE_JFNK: Newton iterate / total, ',
306 & 'JFNKgamma_lin, initial norm = ',
307 & newtonIter, totalNewtonItersLoc,
308 & JFNKgamma_lin,JFNKresidual
309 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
310 & SQUEEZE_RIGHT, myThid )
311 WRITE(msgBuf,'(3(A,I6))')
312 & ' S/R SEAICE_JFNK: Newton iterate / total = ',newtonIter,
313 & ' / ', totalNewtonItersLoc,
314 & ', Nb. of FGMRES iterations = ', krylovIter
315 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
316 & SQUEEZE_RIGHT, myThid )
317 _END_MASTER( myThid )
318 ENDIF
319 IF ( krylovIter.EQ.SEAICElinearIterMax ) THEN
320 krylovFails = krylovFails + 1
321 ENDIF
322 C Set the stopping criterion for the Newton iteration and the
323 C criterion for the transition from accurate to approximate FGMRES
324 IF ( newtonIter .EQ. 1 ) THEN
325 JFNKtol=SEAICEnonLinTol*JFNKresidual
326 IF ( JFNKres_tFac .NE. UNSET_RL )
327 & JFNKres_t = JFNKresidual * JFNKres_tFac
328 ENDIF
329 C Update linear solution vector and return to Newton iteration
330 C Do a linesearch if necessary, and compute a new residual.
331 C Note that it should be possible to do the following operations
332 C at the beginning of the Newton iteration, thereby saving us from
333 C the extra call of seaice_jfnk_update, but unfortunately that
334 C changes the results, so we leave the stuff here for now.
335 CALL SEAICE_JFNK_UPDATE(
336 I duIce, dvIce,
337 U uIce, vIce, JFNKresidual,
338 O uIceRes, vIceRes,
339 I newtonIter, myTime, myIter, myThid )
340 C reset du/vIce here instead of setting sol = 0 in seaice_fgmres_driver
341 DO bj=myByLo(myThid),myByHi(myThid)
342 DO bi=myBxLo(myThid),myBxHi(myThid)
343 DO J=1-OLy,sNy+OLy
344 DO I=1-OLx,sNx+OLx
345 duIce(I,J,bi,bj)= 0. _d 0
346 dvIce(I,J,bi,bj)= 0. _d 0
347 ENDDO
348 ENDDO
349 ENDDO
350 ENDDO
351 ENDIF
352 C end of Newton iterate
353 ENDDO
354
355 C-- Output diagnostics
356
357 IF ( SEAICE_monFreq .GT. 0. _d 0 ) THEN
358 C Count iterations
359 totalJFNKtimeSteps = totalJFNKtimeSteps + 1
360 totalNewtonIters = totalNewtonIters + newtonIter
361 totalKrylovIters = totalKrylovIters + totalKrylovItersLoc
362 C Record failure
363 totalKrylovFails = totalKrylovFails + krylovFails
364 IF ( newtonIter .EQ. SEAICEnonLinIterMax ) THEN
365 totalNewtonFails = totalNewtonFails + 1
366 ENDIF
367 ENDIF
368 C Decide whether it is time to dump and reset the counter
369 writeNow = DIFFERENT_MULTIPLE(SEAICE_monFreq,
370 & myTime+deltaTClock, deltaTClock)
371 #ifdef ALLOW_CAL
372 IF ( useCAL ) THEN
373 CALL CAL_TIME2DUMP(
374 I zeroRL, SEAICE_monFreq, deltaTClock,
375 U writeNow,
376 I myTime+deltaTclock, myIter+1, myThid )
377 ENDIF
378 #endif
379 IF ( writeNow ) THEN
380 _BEGIN_MASTER( myThid )
381 WRITE(msgBuf,'(A)')
382 &' // ======================================================='
383 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
384 & SQUEEZE_RIGHT, myThid )
385 WRITE(msgBuf,'(A)') ' // Begin JFNK statistics'
386 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
387 & SQUEEZE_RIGHT, myThid )
388 WRITE(msgBuf,'(A)')
389 &' // ======================================================='
390 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
391 & SQUEEZE_RIGHT, myThid )
392 WRITE(msgBuf,'(A,I10)')
393 & ' %JFNK_MON: time step = ', myIter+1
394 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
395 & SQUEEZE_RIGHT, myThid )
396 WRITE(msgBuf,'(A,I10)')
397 & ' %JFNK_MON: Nb. of time steps = ', totalJFNKtimeSteps
398 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
399 & SQUEEZE_RIGHT, myThid )
400 WRITE(msgBuf,'(A,I10)')
401 & ' %JFNK_MON: Nb. of Newton steps = ', totalNewtonIters
402 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
403 & SQUEEZE_RIGHT, myThid )
404 WRITE(msgBuf,'(A,I10)')
405 & ' %JFNK_MON: Nb. of Krylov steps = ', totalKrylovIters
406 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
407 & SQUEEZE_RIGHT, myThid )
408 WRITE(msgBuf,'(A,I10)')
409 & ' %JFNK_MON: Nb. of Newton failures = ', totalNewtonFails
410 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
411 & SQUEEZE_RIGHT, myThid )
412 WRITE(msgBuf,'(A,I10)')
413 & ' %JFNK_MON: Nb. of Krylov failures = ', totalKrylovFails
414 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
415 & SQUEEZE_RIGHT, myThid )
416 WRITE(msgBuf,'(A)')
417 &' // ======================================================='
418 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
419 & SQUEEZE_RIGHT, myThid )
420 WRITE(msgBuf,'(A)') ' // End JFNK statistics'
421 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
422 & SQUEEZE_RIGHT, myThid )
423 WRITE(msgBuf,'(A)')
424 &' // ======================================================='
425 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
426 & SQUEEZE_RIGHT, myThid )
427 _END_MASTER( myThid )
428 C reset and start again
429 totalJFNKtimeSteps = 0
430 totalNewtonIters = 0
431 totalKrylovIters = 0
432 totalKrylovFails = 0
433 totalNewtonFails = 0
434 ENDIF
435
436 C Print more debugging information
437 IF ( debugLevel.GE.debLevA ) THEN
438 IF ( newtonIter .EQ. SEAICEnonLinIterMax ) THEN
439 _BEGIN_MASTER( myThid )
440 WRITE(msgBuf,'(A,I10)')
441 & ' S/R SEAICE_JFNK: JFNK did not converge in timestep ',
442 & myIter+1
443 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
444 & SQUEEZE_RIGHT, myThid )
445 _END_MASTER( myThid )
446 ENDIF
447 IF ( krylovFails .GT. 0 ) THEN
448 _BEGIN_MASTER( myThid )
449 WRITE(msgBuf,'(A,I4,A,I10)')
450 & ' S/R SEAICE_JFNK: FGMRES did not converge ',
451 & krylovFails, ' times in timestep ', myIter+1
452 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
453 & SQUEEZE_RIGHT, myThid )
454 _END_MASTER( myThid )
455 ENDIF
456 _BEGIN_MASTER( myThid )
457 WRITE(msgBuf,'(A,I6,A,I10)')
458 & ' S/R SEAICE_JFNK: Total number FGMRES iterations = ',
459 & totalKrylovItersLoc, ' in timestep ', myIter+1
460 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
461 & SQUEEZE_RIGHT, myThid )
462 _END_MASTER( myThid )
463 ENDIF
464
465 RETURN
466 END
467
468 C---+----1----+----2----+----3----+----4----+----5----+----6----+----7-|--+----|
469 CBOP
470 C !ROUTINE: SEAICE_JFNK_UPDATE
471 C !INTERFACE:
472
473 SUBROUTINE SEAICE_JFNK_UPDATE(
474 I duIce, dvIce,
475 U uIce, vIce, JFNKresidual,
476 O uIceRes, vIceRes,
477 I newtonIter, myTime, myIter, myThid )
478
479 C !DESCRIPTION: \bv
480 C *==========================================================*
481 C | SUBROUTINE SEAICE_JFNK_UPDATE
482 C | o Update velocities with incremental solutions of FGMRES
483 C | o compute residual of updated solutions and do
484 C | o linesearch:
485 C | reduce update until residual is smaller than previous
486 C | one (input)
487 C *==========================================================*
488 C | written by Martin Losch, Jan 2013
489 C *==========================================================*
490 C \ev
491
492 C !USES:
493 IMPLICIT NONE
494
495 C === Global variables ===
496 #include "SIZE.h"
497 #include "EEPARAMS.h"
498 #include "PARAMS.h"
499 #include "SEAICE_SIZE.h"
500 #include "SEAICE_PARAMS.h"
501
502 C !INPUT/OUTPUT PARAMETERS:
503 C === Routine arguments ===
504 C myTime :: Simulation time
505 C myIter :: Simulation timestep number
506 C myThid :: my Thread Id. number
507 C newtonIter :: current iterate of Newton iteration
508 _RL myTime
509 INTEGER myIter
510 INTEGER myThid
511 INTEGER newtonIter
512 C JFNKresidual :: Residual at the beginning of the FGMRES iteration,
513 C changes with newtonIter (updated)
514 _RL JFNKresidual
515 C du/vIce :: ice velocity increment to be added to u/vIce (input)
516 _RL duIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
517 _RL dvIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
518 C u/vIce :: ice velocity increment to be added to u/vIce (updated)
519 _RL uIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
520 _RL vIce (1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
521 C u/vIceRes :: residual of sea-ice momentum equations (output)
522 _RL uIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
523 _RL vIceRes(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy)
524
525 C !LOCAL VARIABLES:
526 C === Local variables ===
527 C i,j,bi,bj :: loop indices
528 INTEGER i,j,bi,bj
529 INTEGER l
530 _RL resLoc, facLS
531 LOGICAL doLineSearch
532 C nVec :: size of the input vector(s)
533 C resTmp :: vector version of the residuals
534 INTEGER nVec
535 PARAMETER ( nVec = 2*sNx*sNy )
536 _RL resTmp (nVec,1,nSx,nSy)
537
538 CHARACTER*(MAX_LEN_MBUF) msgBuf
539 CEOP
540
541 C Initialise some local variables
542 l = 0
543 resLoc = JFNKresidual
544 facLS = 1. _d 0
545 doLineSearch = .TRUE.
546 DO WHILE ( doLineSearch )
547 C Create update
548 DO bj=myByLo(myThid),myByHi(myThid)
549 DO bi=myBxLo(myThid),myBxHi(myThid)
550 DO J=1-OLy,sNy+OLy
551 DO I=1-OLx,sNx+OLx
552 uIce(I,J,bi,bj) = uIce(I,J,bi,bj)+facLS*duIce(I,J,bi,bj)
553 vIce(I,J,bi,bj) = vIce(I,J,bi,bj)+facLS*dvIce(I,J,bi,bj)
554 ENDDO
555 ENDDO
556 ENDDO
557 ENDDO
558 C Compute current residual F(u), (includes re-computation of global
559 C variables DWATN, zeta, and eta, i.e. they are different after this)
560 CALL SEAICE_CALC_RESIDUAL(
561 I uIce, vIce,
562 O uIceRes, vIceRes,
563 I newtonIter, 0, myTime, myIter, myThid )
564 C Important: Compute the norm of the residual using the same scalar
565 C product that SEAICE_FGMRES does
566 CALL SEAICE_MAP2VEC(nVec,uIceRes,vIceRes,resTmp,.TRUE.,myThid)
567 CALL SEAICE_SCALPROD(nVec,1,1,1,resTmp,resTmp,resLoc,myThid)
568 resLoc = SQRT(resLoc)
569 C Determine, if we need more iterations
570 doLineSearch = resLoc .GE. JFNKresidual
571 C Limit the maximum number of iterations arbitrarily to four
572 doLineSearch = doLineSearch .AND. l .LT. 4
573 C For the first iteration du/vIce = 0 and there will be no
574 C improvement of the residual possible, so we do only the first
575 C iteration
576 IF ( newtonIter .EQ. 1 ) doLineSearch = .FALSE.
577 C Only start a linesearch after some Newton iterations
578 IF ( newtonIter .LE. SEAICE_JFNK_lsIter ) doLineSearch = .FALSE.
579 C Increment counter
580 l = l + 1
581 C some output diagnostics
582 IF ( debugLevel.GE.debLevA .AND. doLineSearch ) THEN
583 _BEGIN_MASTER( myThid )
584 WRITE(msgBuf,'(2A,2(1XI6),3E12.5)')
585 & ' S/R SEAICE_JFNK_UPDATE: Newton iter, LSiter, ',
586 & 'facLS, JFNKresidual, resLoc = ',
587 & newtonIter, l, facLS, JFNKresidual, resLoc
588 CALL PRINT_MESSAGE( msgBuf, standardMessageUnit,
589 & SQUEEZE_RIGHT, myThid )
590 _END_MASTER( myThid )
591 ENDIF
592 C Get ready for the next iteration: after adding du/vIce in the first
593 C iteration, we substract 0.5*du/vIce from u/vIce in the next
594 C iterations, 0.25*du/vIce in the second, etc.
595 facLS = - 0.5 _d 0 * ABS(facLS)
596 ENDDO
597 C This is the new residual
598 JFNKresidual = resLoc
599
600 #endif /* SEAICE_ALLOW_JFNK */
601
602 RETURN
603 END

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