Actual source code: chwirut2f.F90

  1: !  Program usage: mpiexec -n 1 chwirut1f [-help] [all TAO options]
  2: !
  3: !  Description:  This example demonstrates use of the TAO package to solve a
  4: !  nonlinear least-squares problem on a single processor.  We minimize the
  5: !  Chwirut function:
  6: !       sum_{i=0}^{n/2-1} ( alpha*(x_{2i+1}-x_{2i}^2)^2 + (1-x_{2i})^2)
  7: !
  8: !  The C version of this code is chwirut1.c
  9: !
 10: !!/*T
 11: !  Concepts: TAO^Solving an unconstrained minimization problem
 12: !  Routines: TaoCreate();
 13: !  Routines: TaoSetType();
 14: !  Routines: TaoSetResidualRoutine();
 15: !  Routines: TaoSetInitialVector();
 16: !  Routines: TaoSetFromOptions();
 17: !  Routines: TaoSolve();
 18: !  Routines: TaoDestroy();
 19: !  Processors: n
 20: !T*/

 22: !
 23: ! ----------------------------------------------------------------------
 24: !
 25: #include "chwirut2f.h"

 27: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 28: !                   Variable declarations
 29: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 30: !
 31: !  See additional variable declarations in the file chwirut2f.h

 33:       PetscErrorCode   ierr    ! used to check for functions returning nonzeros
 34:       Vec              x       ! solution vector
 35:       Vec              f       ! vector of functions
 36:       Tao        tao     ! Tao context

 38: !  Note: Any user-defined Fortran routines (such as FormGradient)
 39: !  MUST be declared as external.

 41:       external FormFunction

 43: !  Initialize TAO and PETSc
 44:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
 45:       if (ierr .ne. 0) then
 46:          print*,'Unable to initialize PETSc'
 47:          stop
 48:       endif

 50:       call MPI_Comm_size(PETSC_COMM_WORLD,size,ierr)
 51:       CHKERRA(ierr)
 52:       call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)
 53:       CHKERRA(ierr)

 55: !  Initialize problem parameters
 56:       call InitializeData()

 58:       if (rank .eq. 0) then
 59: !  Allocate vectors for the solution and gradient
 60:          call VecCreateSeq(PETSC_COMM_SELF,n,x,ierr)
 61:          CHKERRA(ierr)
 62:          call VecCreateSeq(PETSC_COMM_SELF,m,f,ierr)
 63:          CHKERRA(ierr)

 65: !     The TAO code begins here

 67: !     Create TAO solver
 68:          call TaoCreate(PETSC_COMM_SELF,tao,ierr)
 69:          CHKERRA(ierr)
 70:          call TaoSetType(tao,TAOPOUNDERS,ierr)
 71:          CHKERRA(ierr)

 73: !     Set routines for function, gradient, and hessian evaluation
 74:          call TaoSetResidualRoutine(tao,f,                    &
 75:      &        FormFunction,0,ierr)
 76:          CHKERRA(ierr)

 78: !     Optional: Set initial guess
 79:          call FormStartingPoint(x)
 80:          call TaoSetInitialVector(tao, x, ierr)
 81:          CHKERRA(ierr)

 83: !     Check for TAO command line options
 84:          call TaoSetFromOptions(tao,ierr)
 85:          CHKERRA(ierr)
 86: !     SOLVE THE APPLICATION
 87:          call TaoSolve(tao,ierr)
 88:          CHKERRA(ierr)

 90: !     Free TAO data structures
 91:          call TaoDestroy(tao,ierr)
 92:          CHKERRA(ierr)

 94: !     Free PETSc data structures
 95:          call VecDestroy(x,ierr)
 96:          CHKERRA(ierr)
 97:          call VecDestroy(f,ierr)
 98:          CHKERRA(ierr)
 99:          call StopWorkers(ierr)
100:          CHKERRA(ierr)

102:       else
103:          call TaskWorker(ierr)
104:          CHKERRA(ierr)
105:       endif

107:       call PetscFinalize(ierr)
108:       end

110: ! --------------------------------------------------------------------
111: !  FormFunction - Evaluates the function f(X) and gradient G(X)
112: !
113: !  Input Parameters:
114: !  tao - the Tao context
115: !  X   - input vector
116: !  dummy - not used
117: !
118: !  Output Parameters:
119: !  f - function vector

121:       subroutine FormFunction(tao, x, f, dummy, ierr)
122: #include "chwirut2f.h"

124:       Tao        tao
125:       Vec              x,f
126:       PetscErrorCode   ierr

128:       PetscInt         i,checkedin
129:       PetscInt         finished_tasks
130:       PetscMPIInt      next_task
131:       PetscMPIInt      status(MPI_STATUS_SIZE),tag,source
132:       PetscInt         dummy

134: ! PETSc's VecGetArray acts differently in Fortran than it does in C.
135: ! Calling VecGetArray((Vec) X, (PetscReal) x_array(0:1), (PetscOffset) x_index, ierr)
136: ! will return an array of doubles referenced by x_array offset by x_index.
137: !  i.e.,  to reference the kth element of X, use x_array(k + x_index).
138: ! Notice that by declaring the arrays with range (0:1), we are using the C 0-indexing practice.
139:       PetscReal        f_v(0:1),x_v(0:1),fval(1)
140:       PetscOffset      f_i,x_i

142:       0

144: !     Get pointers to vector data
145:       call VecGetArray(x,x_v,x_i,ierr)
146:       CHKERRQ(ierr)
147:       call VecGetArray(f,f_v,f_i,ierr)
148:       CHKERRQ(ierr)

150: !     Compute F(X)
151:       if (size .eq. 1) then
152:          ! Single processor
153:          do i=0,m-1
154:             call RunSimulation(x_v(x_i),i,f_v(i+f_i),ierr)
155:          enddo
156:       else
157:          ! Multiprocessor main
158:          next_task = zero
159:          finished_tasks = 0
160:          checkedin = 0

162:          do while (finished_tasks .lt. m .or. checkedin .lt. size-1)
163:             call MPI_Recv(fval,one,MPIU_SCALAR,MPI_ANY_SOURCE,               &
164:      &           MPI_ANY_TAG,PETSC_COMM_WORLD,status,ierr)
165:             tag = status(MPI_TAG)
166:             source = status(MPI_SOURCE)
167:             if (tag .eq. IDLE_TAG) then
168:                checkedin = checkedin + 1
169:             else
170:                f_v(f_i+tag) = fval(1)
171:                finished_tasks = finished_tasks + 1
172:             endif
173:             if (next_task .lt. m) then
174:                ! Send task to worker
175:                call MPI_Send(x_v(x_i),nn,MPIU_SCALAR,source,next_task,             &
176:      &              PETSC_COMM_WORLD,ierr)
177:                next_task = next_task + one
178:             else
179:                ! Send idle message to worker
180:                call MPI_Send(x_v(x_i),nn,MPIU_SCALAR,source,IDLE_TAG,              &
181:      &              PETSC_COMM_WORLD,ierr)
182:             end if
183:          enddo
184:       endif

186: !     Restore vectors
187:       call VecRestoreArray(x,x_v,x_i,ierr)
188:       CHKERRQ(ierr)
189:       call VecRestoreArray(F,f_v,f_i,ierr)
190:       CHKERRQ(ierr)
191:       return
192:       end

194:       subroutine FormStartingPoint(x)
195: #include "chwirut2f.h"

197:       Vec             x
198:       PetscReal       x_v(0:1)
199:       PetscOffset     x_i
200:       PetscErrorCode  ierr

202:       call VecGetArray(x,x_v,x_i,ierr)
203:       CHKERRQ(ierr)
204:       x_v(x_i) = 0.15
205:       x_v(x_i+1) = 0.008
206:       x_v(x_i+2) = 0.01
207:       call VecRestoreArray(x,x_v,x_i,ierr)
208:       CHKERRQ(ierr)
209:       return
210:       end

212:       subroutine InitializeData()
213: #include "chwirut2f.h"

215:       PetscInt i
216:       i=0
217:       y(i) =    92.9000;  t(i) =  0.5000; i=i+1
218:       y(i) =    78.7000;  t(i) =   0.6250; i=i+1
219:       y(i) =    64.2000;  t(i) =   0.7500; i=i+1
220:       y(i) =    64.9000;  t(i) =   0.8750; i=i+1
221:       y(i) =    57.1000;  t(i) =   1.0000; i=i+1
222:       y(i) =    43.3000;  t(i) =   1.2500; i=i+1
223:       y(i) =    31.1000;  t(i) =  1.7500; i=i+1
224:       y(i) =    23.6000;  t(i) =  2.2500; i=i+1
225:       y(i) =    31.0500;  t(i) =  1.7500; i=i+1
226:       y(i) =    23.7750;  t(i) =  2.2500; i=i+1
227:       y(i) =    17.7375;  t(i) =  2.7500; i=i+1
228:       y(i) =    13.8000;  t(i) =  3.2500; i=i+1
229:       y(i) =    11.5875;  t(i) =  3.7500; i=i+1
230:       y(i) =     9.4125;  t(i) =  4.2500; i=i+1
231:       y(i) =     7.7250;  t(i) =  4.7500; i=i+1
232:       y(i) =     7.3500;  t(i) =  5.2500; i=i+1
233:       y(i) =     8.0250;  t(i) =  5.7500; i=i+1
234:       y(i) =    90.6000;  t(i) =  0.5000; i=i+1
235:       y(i) =    76.9000;  t(i) =  0.6250; i=i+1
236:       y(i) =    71.6000;  t(i) = 0.7500; i=i+1
237:       y(i) =    63.6000;  t(i) =  0.8750; i=i+1
238:       y(i) =    54.0000;  t(i) =  1.0000; i=i+1
239:       y(i) =    39.2000;  t(i) =  1.2500; i=i+1
240:       y(i) =    29.3000;  t(i) = 1.7500; i=i+1
241:       y(i) =    21.4000;  t(i) =  2.2500; i=i+1
242:       y(i) =    29.1750;  t(i) =  1.7500; i=i+1
243:       y(i) =    22.1250;  t(i) =  2.2500; i=i+1
244:       y(i) =    17.5125;  t(i) =  2.7500; i=i+1
245:       y(i) =    14.2500;  t(i) =  3.2500; i=i+1
246:       y(i) =     9.4500;  t(i) =  3.7500; i=i+1
247:       y(i) =     9.1500;  t(i) =  4.2500; i=i+1
248:       y(i) =     7.9125;  t(i) =  4.7500; i=i+1
249:       y(i) =     8.4750;  t(i) =  5.2500; i=i+1
250:       y(i) =     6.1125;  t(i) =  5.7500; i=i+1
251:       y(i) =    80.0000;  t(i) =  0.5000; i=i+1
252:       y(i) =    79.0000;  t(i) =  0.6250; i=i+1
253:       y(i) =    63.8000;  t(i) =  0.7500; i=i+1
254:       y(i) =    57.2000;  t(i) =  0.8750; i=i+1
255:       y(i) =    53.2000;  t(i) =  1.0000; i=i+1
256:       y(i) =    42.5000;  t(i) =  1.2500; i=i+1
257:       y(i) =    26.8000;  t(i) =  1.7500; i=i+1
258:       y(i) =    20.4000;  t(i) =  2.2500; i=i+1
259:       y(i) =    26.8500;  t(i) =   1.7500; i=i+1
260:       y(i) =    21.0000;  t(i) =   2.2500; i=i+1
261:       y(i) =    16.4625;  t(i) =   2.7500; i=i+1
262:       y(i) =    12.5250;  t(i) =   3.2500; i=i+1
263:       y(i) =    10.5375;  t(i) =   3.7500; i=i+1
264:       y(i) =     8.5875;  t(i) =   4.2500; i=i+1
265:       y(i) =     7.1250;  t(i) =   4.7500; i=i+1
266:       y(i) =     6.1125;  t(i) =   5.2500; i=i+1
267:       y(i) =     5.9625;  t(i) =   5.7500; i=i+1
268:       y(i) =    74.1000;  t(i) =   0.5000; i=i+1
269:       y(i) =    67.3000;  t(i) =   0.6250; i=i+1
270:       y(i) =    60.8000;  t(i) =   0.7500; i=i+1
271:       y(i) =    55.5000;  t(i) =   0.8750; i=i+1
272:       y(i) =    50.3000;  t(i) =   1.0000; i=i+1
273:       y(i) =    41.0000;  t(i) =   1.2500; i=i+1
274:       y(i) =    29.4000;  t(i) =   1.7500; i=i+1
275:       y(i) =    20.4000;  t(i) =   2.2500; i=i+1
276:       y(i) =    29.3625;  t(i) =   1.7500; i=i+1
277:       y(i) =    21.1500;  t(i) =   2.2500; i=i+1
278:       y(i) =    16.7625;  t(i) =   2.7500; i=i+1
279:       y(i) =    13.2000;  t(i) =   3.2500; i=i+1
280:       y(i) =    10.8750;  t(i) =   3.7500; i=i+1
281:       y(i) =     8.1750;  t(i) =   4.2500; i=i+1
282:       y(i) =     7.3500;  t(i) =   4.7500; i=i+1
283:       y(i) =     5.9625;  t(i) =  5.2500; i=i+1
284:       y(i) =     5.6250;  t(i) =   5.7500; i=i+1
285:       y(i) =    81.5000;  t(i) =    .5000; i=i+1
286:       y(i) =    62.4000;  t(i) =    .7500; i=i+1
287:       y(i) =    32.5000;  t(i) =   1.5000; i=i+1
288:       y(i) =    12.4100;  t(i) =   3.0000; i=i+1
289:       y(i) =    13.1200;  t(i) =   3.0000; i=i+1
290:       y(i) =    15.5600;  t(i) =   3.0000; i=i+1
291:       y(i) =     5.6300;  t(i) =   6.0000; i=i+1
292:       y(i) =    78.0000;  t(i) =   .5000; i=i+1
293:       y(i) =    59.9000;  t(i) =    .7500; i=i+1
294:       y(i) =    33.2000;  t(i) =   1.5000; i=i+1
295:       y(i) =    13.8400;  t(i) =   3.0000; i=i+1
296:       y(i) =    12.7500;  t(i) =   3.0000; i=i+1
297:       y(i) =    14.6200;  t(i) =   3.0000; i=i+1
298:       y(i) =     3.9400;  t(i) =   6.0000; i=i+1
299:       y(i) =    76.8000;  t(i) =    .5000; i=i+1
300:       y(i) =    61.0000;  t(i) =    .7500; i=i+1
301:       y(i) =    32.9000;  t(i) =   1.5000; i=i+1
302:       y(i) =    13.8700;  t(i) = 3.0000; i=i+1
303:       y(i) =    11.8100;  t(i) =   3.0000; i=i+1
304:       y(i) =    13.3100;  t(i) =   3.0000; i=i+1
305:       y(i) =     5.4400;  t(i) =   6.0000; i=i+1
306:       y(i) =    78.0000;  t(i) =    .5000; i=i+1
307:       y(i) =    63.5000;  t(i) =    .7500; i=i+1
308:       y(i) =    33.8000;  t(i) =   1.5000; i=i+1
309:       y(i) =    12.5600;  t(i) =   3.0000; i=i+1
310:       y(i) =     5.6300;  t(i) =   6.0000; i=i+1
311:       y(i) =    12.7500;  t(i) =   3.0000; i=i+1
312:       y(i) =    13.1200;  t(i) =   3.0000; i=i+1
313:       y(i) =     5.4400;  t(i) =   6.0000; i=i+1
314:       y(i) =    76.8000;  t(i) =    .5000; i=i+1
315:       y(i) =    60.0000;  t(i) =    .7500; i=i+1
316:       y(i) =    47.8000;  t(i) =   1.0000; i=i+1
317:       y(i) =    32.0000;  t(i) =   1.5000; i=i+1
318:       y(i) =    22.2000;  t(i) =   2.0000; i=i+1
319:       y(i) =    22.5700;  t(i) =   2.0000; i=i+1
320:       y(i) =    18.8200;  t(i) =   2.5000; i=i+1
321:       y(i) =    13.9500;  t(i) =   3.0000; i=i+1
322:       y(i) =    11.2500;  t(i) =   4.0000; i=i+1
323:       y(i) =     9.0000;  t(i) =   5.0000; i=i+1
324:       y(i) =     6.6700;  t(i) =   6.0000; i=i+1
325:       y(i) =    75.8000;  t(i) =    .5000; i=i+1
326:       y(i) =    62.0000;  t(i) =    .7500; i=i+1
327:       y(i) =    48.8000;  t(i) =   1.0000; i=i+1
328:       y(i) =    35.2000;  t(i) =   1.5000; i=i+1
329:       y(i) =    20.0000;  t(i) =   2.0000; i=i+1
330:       y(i) =    20.3200;  t(i) =   2.0000; i=i+1
331:       y(i) =    19.3100;  t(i) =   2.5000; i=i+1
332:       y(i) =    12.7500;  t(i) =   3.0000; i=i+1
333:       y(i) =    10.4200;  t(i) =   4.0000; i=i+1
334:       y(i) =     7.3100;  t(i) =   5.0000; i=i+1
335:       y(i) =     7.4200;  t(i) =   6.0000; i=i+1
336:       y(i) =    70.5000;  t(i) =    .5000; i=i+1
337:       y(i) =    59.5000;  t(i) =    .7500; i=i+1
338:       y(i) =    48.5000;  t(i) =   1.0000; i=i+1
339:       y(i) =    35.8000;  t(i) =   1.5000; i=i+1
340:       y(i) =    21.0000;  t(i) =   2.0000; i=i+1
341:       y(i) =    21.6700;  t(i) =   2.0000; i=i+1
342:       y(i) =    21.0000;  t(i) =   2.5000; i=i+1
343:       y(i) =    15.6400;  t(i) =   3.0000; i=i+1
344:       y(i) =     8.1700;  t(i) =   4.0000; i=i+1
345:       y(i) =     8.5500;  t(i) =   5.0000; i=i+1
346:       y(i) =    10.1200;  t(i) =   6.0000; i=i+1
347:       y(i) =    78.0000;  t(i) =    .5000; i=i+1
348:       y(i) =    66.0000;  t(i) =    .6250; i=i+1
349:       y(i) =    62.0000;  t(i) =    .7500; i=i+1
350:       y(i) =    58.0000;  t(i) =    .8750; i=i+1
351:       y(i) =    47.7000;  t(i) =   1.0000; i=i+1
352:       y(i) =    37.8000;  t(i) =   1.2500; i=i+1
353:       y(i) =    20.2000;  t(i) =   2.2500; i=i+1
354:       y(i) =    21.0700;  t(i) =   2.2500; i=i+1
355:       y(i) =    13.8700;  t(i) =   2.7500; i=i+1
356:       y(i) =     9.6700;  t(i) =   3.2500; i=i+1
357:       y(i) =     7.7600;  t(i) =   3.7500; i=i+1
358:       y(i) =     5.4400;  t(i) =  4.2500; i=i+1
359:       y(i) =     4.8700;  t(i) =  4.7500; i=i+1
360:       y(i) =     4.0100;  t(i) =   5.2500; i=i+1
361:       y(i) =     3.7500;  t(i) =   5.7500; i=i+1
362:       y(i) =    24.1900;  t(i) =   3.0000; i=i+1
363:       y(i) =    25.7600;  t(i) =   3.0000; i=i+1
364:       y(i) =    18.0700;  t(i) =   3.0000; i=i+1
365:       y(i) =    11.8100;  t(i) =   3.0000; i=i+1
366:       y(i) =    12.0700;  t(i) =   3.0000; i=i+1
367:       y(i) =    16.1200;  t(i) =   3.0000; i=i+1
368:       y(i) =    70.8000;  t(i) =    .5000; i=i+1
369:       y(i) =    54.7000;  t(i) =    .7500; i=i+1
370:       y(i) =    48.0000;  t(i) =   1.0000; i=i+1
371:       y(i) =    39.8000;  t(i) =   1.5000; i=i+1
372:       y(i) =    29.8000;  t(i) =   2.0000; i=i+1
373:       y(i) =    23.7000;  t(i) =   2.5000; i=i+1
374:       y(i) =    29.6200;  t(i) =   2.0000; i=i+1
375:       y(i) =    23.8100;  t(i) =   2.5000; i=i+1
376:       y(i) =    17.7000;  t(i) =   3.0000; i=i+1
377:       y(i) =    11.5500;  t(i) =   4.0000; i=i+1
378:       y(i) =    12.0700;  t(i) =   5.0000; i=i+1
379:       y(i) =     8.7400;  t(i) =   6.0000; i=i+1
380:       y(i) =    80.7000;  t(i) =    .5000; i=i+1
381:       y(i) =    61.3000;  t(i) =    .7500; i=i+1
382:       y(i) =    47.5000;  t(i) =   1.0000; i=i+1
383:       y(i) =    29.0000;  t(i) =   1.5000; i=i+1
384:       y(i) =    24.0000;  t(i) =   2.0000; i=i+1
385:       y(i) =    17.7000;  t(i) =   2.5000; i=i+1
386:       y(i) =    24.5600;  t(i) =   2.0000; i=i+1
387:       y(i) =    18.6700;  t(i) =   2.5000; i=i+1
388:       y(i) =    16.2400;  t(i) =   3.0000; i=i+1
389:       y(i) =     8.7400;  t(i) =   4.0000; i=i+1
390:       y(i) =     7.8700;  t(i) =   5.0000; i=i+1
391:       y(i) =     8.5100;  t(i) =   6.0000; i=i+1
392:       y(i) =    66.7000;  t(i) =    .5000; i=i+1
393:       y(i) =    59.2000;  t(i) =    .7500; i=i+1
394:       y(i) =    40.8000;  t(i) =   1.0000; i=i+1
395:       y(i) =    30.7000;  t(i) =   1.5000; i=i+1
396:       y(i) =    25.7000;  t(i) =   2.0000; i=i+1
397:       y(i) =    16.3000;  t(i) =   2.5000; i=i+1
398:       y(i) =    25.9900;  t(i) =   2.0000; i=i+1
399:       y(i) =    16.9500;  t(i) =   2.5000; i=i+1
400:       y(i) =    13.3500;  t(i) =   3.0000; i=i+1
401:       y(i) =     8.6200;  t(i) =   4.0000; i=i+1
402:       y(i) =     7.2000;  t(i) =   5.0000; i=i+1
403:       y(i) =     6.6400;  t(i) =   6.0000; i=i+1
404:       y(i) =    13.6900;  t(i) =   3.0000; i=i+1
405:       y(i) =    81.0000;  t(i) =    .5000; i=i+1
406:       y(i) =    64.5000;  t(i) =    .7500; i=i+1
407:       y(i) =    35.5000;  t(i) =   1.5000; i=i+1
408:       y(i) =    13.3100;  t(i) =   3.0000; i=i+1
409:       y(i) =     4.8700;  t(i) =   6.0000; i=i+1
410:       y(i) =    12.9400;  t(i) =   3.0000; i=i+1
411:       y(i) =     5.0600;  t(i) =   6.0000; i=i+1
412:       y(i) =    15.1900;  t(i) =   3.0000; i=i+1
413:       y(i) =    14.6200;  t(i) =   3.0000; i=i+1
414:       y(i) =    15.6400;  t(i) =   3.0000; i=i+1
415:       y(i) =    25.5000;  t(i) =   1.7500; i=i+1
416:       y(i) =    25.9500;  t(i) =   1.7500; i=i+1
417:       y(i) =    81.7000;  t(i) =    .5000; i=i+1
418:       y(i) =    61.6000;  t(i) =    .7500; i=i+1
419:       y(i) =    29.8000;  t(i) =   1.7500; i=i+1
420:       y(i) =    29.8100;  t(i) =   1.7500; i=i+1
421:       y(i) =    17.1700;  t(i) =   2.7500; i=i+1
422:       y(i) =    10.3900;  t(i) =   3.7500; i=i+1
423:       y(i) =    28.4000;  t(i) =   1.7500; i=i+1
424:       y(i) =    28.6900;  t(i) =   1.7500; i=i+1
425:       y(i) =    81.3000;  t(i) =    .5000; i=i+1
426:       y(i) =    60.9000;  t(i) =    .7500; i=i+1
427:       y(i) =    16.6500;  t(i) =   2.7500; i=i+1
428:       y(i) =    10.0500;  t(i) =   3.7500; i=i+1
429:       y(i) =    28.9000;  t(i) =   1.7500; i=i+1
430:       y(i) =    28.9500;  t(i) =   1.7500; i=i+1

432:       return
433:       end

435:       subroutine TaskWorker(ierr)
436: #include "chwirut2f.h"

438:       PetscErrorCode ierr
439:       PetscReal x(n),f(1)
440:       PetscMPIInt tag
441:       PetscInt index
442:       PetscMPIInt status(MPI_STATUS_SIZE)

444:       tag = IDLE_TAG
445:       f   = 0.0
446:       ! Send check-in message to rank-0
447:       call MPI_Send(f,one,MPIU_SCALAR,zero,IDLE_TAG,PETSC_COMM_WORLD,ierr)
448:       CHKERRQ(ierr)
449:       do while (tag .ne. DIE_TAG)
450:          call MPI_Recv(x,nn,MPIU_SCALAR,zero,MPI_ANY_TAG,PETSC_COMM_WORLD,     &
451:      &        status,ierr)
452:          CHKERRQ(ierr)
453:          tag = status(MPI_TAG)
454:          if (tag .eq. IDLE_TAG) then
455:             call MPI_Send(f,one,MPIU_SCALAR,zero,IDLE_TAG,PETSC_COMM_WORLD,     &
456:      &           ierr)
457:             CHKERRQ(ierr)
458:          else if (tag .ne. DIE_TAG) then
459:             index = tag
460:             ! Compute local part of residual
461:             call RunSimulation(x,index,f(1),ierr)
462:             CHKERRQ(ierr)

464:             ! Return residual to rank-0
465:             call MPI_Send(f,one,MPIU_SCALAR,zero,tag,PETSC_COMM_WORLD,ierr)
466:             CHKERRQ(ierr)
467:          end if
468:       enddo
469:       0
470:       return
471:       end

473:       subroutine RunSimulation(x,i,f,ierr)
474: #include "chwirut2f.h"

476:       PetscReal x(n),f
477:       PetscInt i
478:       PetscErrorCode ierr
479:       f = y(i) - exp(-x(1)*t(i))/(x(2)+x(3)*t(i))
480:       0
481:       return
482:       end

484:       subroutine StopWorkers(ierr)
485: #include "chwirut2f.h"

487:       integer checkedin
488:       PetscMPIInt status(MPI_STATUS_SIZE)
489:       PetscMPIInt source
490:       PetscReal f(1),x(n)
491:       PetscErrorCode ierr
492:       PetscInt i

494:       checkedin=0
495:       do while (checkedin .lt. size-1)
496:          call MPI_Recv(f,one,MPIU_SCALAR,MPI_ANY_SOURCE,MPI_ANY_TAG,         &
497:      &        PETSC_COMM_WORLD,status,ierr)
498:          CHKERRQ(ierr)
499:          checkedin=checkedin+1
500:          source = status(MPI_SOURCE)
501:          do i=1,n
502:            x(i) = 0.0
503:          enddo
504:          call MPI_Send(x,nn,MPIU_SCALAR,source,DIE_TAG,PETSC_COMM_WORLD,    &
505:      &        ierr)
506:          CHKERRQ(ierr)
507:       enddo
508:       0
509:       return
510:       end

512: !/*TEST
513: !
514: !   build:
515: !      requires: !complex
516: !
517: !   test:
518: !      nsize: 3
519: !      args: -tao_smonitor -tao_max_it 100 -tao_type pounders -tao_gatol 1.e-5
520: !      requires: !single
521: !
522: !
523: !TEST*/