/[escript]/trunk/paso/src/Solver.c
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Annotation of /trunk/paso/src/Solver.c

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Revision 1819 - (hide annotations)
Tue Sep 30 05:58:06 2008 UTC (12 years, 11 months ago) by artak
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Firs version of symmetric Gauss-Seidel preconditioner with coloring
1 ksteube 1312
2     /*******************************************************
3 ksteube 1811 *
4     * Copyright (c) 2003-2008 by University of Queensland
5     * Earth Systems Science Computational Center (ESSCC)
6     * http://www.uq.edu.au/esscc
7     *
8     * Primary Business: Queensland, Australia
9     * Licensed under the Open Software License version 3.0
10     * http://www.opensource.org/licenses/osl-3.0.php
11     *
12     *******************************************************/
13 dhawcroft 631
14 ksteube 1811
15 jgs 150 /**************************************************************/
16    
17     /* Paso: SystemMatrix: controls iterative linear system solvers */
18    
19     /**************************************************************/
20    
21     /* Copyrights by ACcESS Australia 2003/04 */
22     /* Author: gross@access.edu.au */
23    
24     /**************************************************************/
25    
26 gross 700 #include "Paso.h"
27     #include "SystemMatrix.h"
28 jgs 150 #include "Solver.h"
29 ksteube 1312 #include "escript/blocktimer.h"
30 jgs 150
31     /***********************************************************************************/
32    
33     /* free space */
34    
35     void Paso_Solver_free(Paso_SystemMatrix* A) {
36 phornby 1628 Paso_Preconditioner_free(A->solver);
37     A->solver=NULL;
38 jgs 150 }
39     /* call the iterative solver: */
40    
41 phornby 1628 void Paso_Solver(Paso_SystemMatrix* A,double* x,double* b,
42     Paso_Options* options,Paso_Performance* pp) {
43    
44     double norm2_of_b,tol,tolerance,time_iter;
45     double *r=NULL,norm2_of_residual,last_norm2_of_residual,norm_max_of_b;
46     double norm2_of_b_local,norm_max_of_b_local,norm2_of_residual_local;
47     double norm_max_of_residual_local,norm_max_of_residual;
48     double last_norm_max_of_residual,*scaling;
49     #ifdef PASO_MPI
50     double loc_norm;
51     #endif
52     dim_t i,totIter,cntIter,method;
53     bool_t finalizeIteration;
54     err_t errorCode;
55     dim_t numSol = Paso_SystemMatrix_getTotalNumCols(A);
56     dim_t numEqua = Paso_SystemMatrix_getTotalNumRows(A);
57 ksteube 1707 double blocktimer_precond, blocktimer_start = blocktimer_time();
58 gross 415
59 gross 1639 tolerance=MAX(options->tolerance,EPSILON);
60     Paso_resetError();
61     method=Paso_Options_getSolver(options->method,PASO_PASO,options->symmetric);
62     /* check matrix type */
63     if ((A->type & MATRIX_FORMAT_CSC) || (A->type & MATRIX_FORMAT_OFFSET1) || (A->type & MATRIX_FORMAT_SYM) ) {
64     Paso_setError(TYPE_ERROR,"Iterative solver requires CSR format with unsymmetric storage scheme and index offset 0.");
65     }
66     if (A->col_block_size != A->row_block_size) {
67     Paso_setError(TYPE_ERROR,"Iterative solver requires row and column block sizes to be equal.");
68     }
69     if (Paso_SystemMatrix_getGlobalNumCols(A) != Paso_SystemMatrix_getGlobalNumRows(A)) {
70 artak 1787 Paso_setError(TYPE_ERROR,"Iterative solver requires a square matrix.");
71 gross 1639 return;
72     }
73     /* this for testing only */
74     if (method==PASO_NONLINEAR_GMRES) {
75     Paso_Function* F=NULL;
76     F=Paso_Function_LinearSystem_alloc(A,b,options);
77 gross 1798 Paso_Solver_solvePreconditioner(A,x,b);
78 gross 1639 errorCode=Paso_Solver_NewtonGMRES(F,x,options,pp);
79 gross 1798 if (errorCode!=NO_ERROR) {
80 gross 1639 Paso_setError(SYSTEM_ERROR,"Paso_Solver_NewtonGMRES: an error has occured.");
81     }
82     Paso_Function_LinearSystem_free(F);
83 gross 1798 return;
84 gross 1639 }
85     /* ========================= */
86     Performance_startMonitor(pp,PERFORMANCE_ALL);
87     if (Paso_noError()) {
88     /* get normalization */
89     scaling=Paso_SystemMatrix_borrowNormalization(A);
90     if (Paso_noError()) {
91     /* get the norm of the right hand side */
92     norm2_of_b=0.;
93     norm_max_of_b=0.;
94     #pragma omp parallel private(norm2_of_b_local,norm_max_of_b_local)
95     {
96     norm2_of_b_local=0.;
97     norm_max_of_b_local=0.;
98     #pragma omp for private(i) schedule(static)
99     for (i = 0; i < numEqua ; ++i) {
100     norm2_of_b_local += b[i] * b[i];
101     norm_max_of_b_local = MAX(ABS(scaling[i]*b[i]),norm_max_of_b_local);
102     }
103     #pragma omp critical
104     {
105     norm2_of_b += norm2_of_b_local;
106     norm_max_of_b = MAX(norm_max_of_b_local,norm_max_of_b);
107     }
108     }
109     /* TODO: use one call */
110     #ifdef PASO_MPI
111     {
112     loc_norm = norm2_of_b;
113     MPI_Allreduce(&loc_norm,&norm2_of_b, 1, MPI_DOUBLE, MPI_SUM, A->mpi_info->comm);
114     loc_norm = norm_max_of_b;
115     MPI_Allreduce(&loc_norm,&norm_max_of_b, 1, MPI_DOUBLE, MPI_MAX, A->mpi_info->comm);
116     }
117     #endif
118     norm2_of_b=sqrt(norm2_of_b);
119 jgs 150
120 phornby 1628 /* if norm2_of_b==0 we are ready: x=0 */
121     if (norm2_of_b <=0.) {
122 gross 1798 #pragma omp parallel for private(i) schedule(static)
123 phornby 1628 for (i = 0; i < numSol; i++) x[i]=0.;
124     if (options->verbose) printf("right hand side is identical zero.\n");
125     } else {
126     if (options->verbose) {
127     printf("l2/lmax-norm of right hand side is %e/%e.\n",norm2_of_b,norm_max_of_b);
128     printf("l2/lmax-stopping criterion is %e/%e.\n",norm2_of_b*tolerance,norm_max_of_b*tolerance);
129     switch (method) {
130     case PASO_BICGSTAB:
131     printf("Iterative method is BiCGStab.\n");
132     break;
133     case PASO_PCG:
134     printf("Iterative method is PCG.\n");
135     break;
136 artak 1703 case PASO_TFQMR:
137     printf("Iterative method is TFQMR.\n");
138     break;
139 artak 1787 case PASO_MINRES:
140     printf("Iterative method is MINRES.\n");
141     break;
142 phornby 1628 case PASO_PRES20:
143     printf("Iterative method is PRES20.\n");
144     break;
145     case PASO_GMRES:
146     if (options->restart>0) {
147     printf("Iterative method is GMRES(%d,%d)\n",options->truncation,options->restart);
148     } else {
149     printf("Iterative method is GMRES(%d)\n",options->truncation);
150 gross 584 }
151 phornby 1628 break;
152     }
153     }
154     /* construct the preconditioner */
155 gross 584
156 ksteube 1707 blocktimer_precond = blocktimer_time();
157 phornby 1628 Performance_startMonitor(pp,PERFORMANCE_PRECONDITIONER_INIT);
158     Paso_Solver_setPreconditioner(A,options);
159     Performance_stopMonitor(pp,PERFORMANCE_PRECONDITIONER_INIT);
160 ksteube 1707 blocktimer_increment("Paso_Solver_setPreconditioner()", blocktimer_precond);
161 phornby 1628 if (! Paso_noError()) return;
162 ksteube 1312 time_iter=Paso_timer();
163 gross 584 /* get an initial guess by evaluating the preconditioner */
164 gross 1556 Paso_Solver_solvePreconditioner(A,x,b);
165 gross 584 /* start the iteration process :*/
166 ksteube 1312 r=TMPMEMALLOC(numEqua,double);
167     Paso_checkPtr(r);
168     if (Paso_noError()) {
169     totIter = 0;
170     finalizeIteration = FALSE;
171     last_norm2_of_residual=norm2_of_b;
172     last_norm_max_of_residual=norm_max_of_b;
173 artak 1787 /* Loop */
174 ksteube 1312 while (! finalizeIteration) {
175     cntIter = options->iter_max - totIter;
176     finalizeIteration = TRUE;
177     /* Set initial residual. */
178     norm2_of_residual = 0;
179     norm_max_of_residual = 0;
180 gross 1556 #pragma omp parallel for private(i) schedule(static)
181     for (i = 0; i < numEqua; i++) r[i]=b[i];
182     Paso_SystemMatrix_MatrixVector_CSR_OFFSET0(DBLE(-1), A, x, DBLE(1), r);
183    
184 ksteube 1312 #pragma omp parallel private(norm2_of_residual_local,norm_max_of_residual_local)
185     {
186     norm2_of_residual_local = 0;
187     norm_max_of_residual_local = 0;
188     #pragma omp for private(i) schedule(static)
189     for (i = 0; i < numEqua; i++) {
190     norm2_of_residual_local+= r[i] * r[i];
191     norm_max_of_residual_local=MAX(ABS(scaling[i]*r[i]),norm_max_of_residual_local);
192     }
193     #pragma omp critical
194     {
195     norm2_of_residual += norm2_of_residual_local;
196     norm_max_of_residual = MAX(norm_max_of_residual_local,norm_max_of_residual);
197     }
198 gross 584 }
199 ksteube 1312 /* TODO: use one call */
200     #ifdef PASO_MPI
201     loc_norm = norm2_of_residual;
202     MPI_Allreduce(&loc_norm,&norm2_of_residual, 1, MPI_DOUBLE, MPI_SUM, A->mpi_info->comm);
203     loc_norm = norm_max_of_residual;
204     MPI_Allreduce(&loc_norm,&norm_max_of_residual, 1, MPI_DOUBLE, MPI_MAX, A->mpi_info->comm);
205     #endif
206     norm2_of_residual =sqrt(norm2_of_residual);
207    
208 phornby 1628 if (options->verbose) printf("Step %5d: l2/lmax-norm of residual is %e/%e",totIter,norm2_of_residual,norm_max_of_residual);
209     if (totIter>0 && norm2_of_residual>=last_norm2_of_residual && norm_max_of_residual>=last_norm_max_of_residual) {
210     if (options->verbose) printf(" divergence!\n");
211     Paso_setError(WARNING, "No improvement during iteration. Iterative solver gives up.");
212     } else {
213     /* */
214     if (norm2_of_residual>tolerance*norm2_of_b || norm_max_of_residual>tolerance*norm_max_of_b ) {
215     tol=tolerance*MIN(norm2_of_b,0.1*norm2_of_residual/norm_max_of_residual*norm_max_of_b);
216     if (options->verbose) printf(" (new tolerance = %e).\n",tol);
217     last_norm2_of_residual=norm2_of_residual;
218     last_norm_max_of_residual=norm_max_of_residual;
219     /* call the solver */
220     switch (method) {
221     case PASO_BICGSTAB:
222     errorCode = Paso_Solver_BiCGStab(A, r, x, &cntIter, &tol, pp);
223     break;
224     case PASO_PCG:
225 artak 1819 errorCode = Paso_Solver_PCG(A, r, x, &cntIter, &tol, pp);
226 phornby 1628 break;
227 artak 1703 case PASO_TFQMR:
228 artak 1787 errorCode = Paso_Solver_TFQMR(A, r, x, &cntIter, &tol, pp);
229 artak 1703 break;
230 artak 1787 case PASO_MINRES:
231     errorCode = Paso_Solver_MINRES(A, r, x, &cntIter, &tolerance, &tol, pp);
232     break;
233 phornby 1628 case PASO_PRES20:
234     errorCode = Paso_Solver_GMRES(A, r, x, &cntIter, &tol,5,20, pp);
235     break;
236     case PASO_GMRES:
237     errorCode = Paso_Solver_GMRES(A, r, x, &cntIter, &tol,options->truncation,options->restart, pp);
238     break;
239     }
240     totIter += cntIter;
241     /* error handling */
242     if (errorCode==NO_ERROR) {
243     finalizeIteration = FALSE;
244     } else if (errorCode==SOLVER_MAXITER_REACHED) {
245     Paso_setError(WARNING,"maximum number of iteration step reached.\nReturned solution does not fulfil stopping criterion.");
246     if (options->verbose) printf("Maximum number of iterations reached.!\n");
247     } else if (errorCode == SOLVER_INPUT_ERROR ) {
248     Paso_setError(SYSTEM_ERROR,"illegal dimension in iterative solver.");
249     if (options->verbose) printf("Internal error!\n");
250     } else if ( errorCode == SOLVER_BREAKDOWN ) {
251     if (cntIter <= 1) {
252     Paso_setError(ZERO_DIVISION_ERROR, "fatal break down in iterative solver.");
253     if (options->verbose) printf("Uncurable break down!\n");
254     } else {
255     if (options->verbose) printf("Breakdown at iter %d (residual = %e). Restarting ...\n", cntIter+totIter, tol);
256     finalizeIteration = FALSE;
257 ksteube 1312 }
258     } else {
259     if (options->verbose) printf(". convergence! \n");
260     }
261 jgs 150 }
262 ksteube 1312 } /* while */
263     }
264 gross 584 MEMFREE(r);
265     time_iter=Paso_timer()-time_iter;
266     if (options->verbose) {
267 gross 1639 printf("\ntiming: solver: %.4e sec\n",time_iter);
268 gross 584 if (totIter>0) printf("timing: per iteration step: %.4e sec\n",time_iter/totIter);
269 jgs 150 }
270     }
271     }
272 gross 584 }
273 phornby 1628 }
274     Performance_stopMonitor(pp,PERFORMANCE_ALL);
275     blocktimer_increment("Paso_Solver()", blocktimer_start);
276 jgs 150 }

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