Actual source code: test11.c
slepc-3.18.3 2023-03-24
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
6: This file is part of SLEPc.
7: SLEPc is distributed under a 2-clause BSD license (see LICENSE).
8: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
9: */
10: /*
11: Example based on spring problem in NLEVP collection [1]. See the parameters
12: meaning at Example 2 in [2].
14: [1] T. Betcke, N. J. Higham, V. Mehrmann, C. Schroder, and F. Tisseur,
15: NLEVP: A Collection of Nonlinear Eigenvalue Problems, MIMS EPrint
16: 2010.98, November 2010.
17: [2] F. Tisseur, Backward error and condition of polynomial eigenvalue
18: problems, Linear Algebra and its Applications, 309 (2000), pp. 339--361,
19: April 2000.
20: */
22: static char help[] = "Illustrates the use of a user-defined stopping test.\n\n"
23: "The command line options are:\n"
24: " -n <n> ... number of grid subdivisions.\n"
25: " -mu <value> ... mass (default 1).\n"
26: " -tau <value> ... damping constant of the dampers (default 10).\n"
27: " -kappa <value> ... damping constant of the springs (default 5).\n\n";
29: #include <slepcpep.h>
31: /*
32: User-defined routines
33: */
34: PetscErrorCode MyStoppingTest(PEP,PetscInt,PetscInt,PetscInt,PetscInt,PEPConvergedReason*,void*);
36: typedef struct {
37: PetscInt lastnconv; /* last value of nconv; used in stopping test */
38: PetscInt nreps; /* number of repetitions of nconv; used in stopping test */
39: } CTX_SPRING;
41: int main(int argc,char **argv)
42: {
43: Mat M,C,K,A[3]; /* problem matrices */
44: PEP pep; /* polynomial eigenproblem solver context */
45: RG rg; /* region object */
46: ST st;
47: CTX_SPRING *ctx;
48: PetscBool terse;
49: PetscViewer viewer;
50: PetscInt n=30,Istart,Iend,i,mpd;
51: PetscReal mu=1.0,tau=10.0,kappa=5.0;
54: SlepcInitialize(&argc,&argv,(char*)0,help);
56: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
57: PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL);
58: PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL);
59: PetscOptionsGetReal(NULL,NULL,"-kappa",&kappa,NULL);
60: PetscPrintf(PETSC_COMM_WORLD,"\nDamped mass-spring system, n=%" PetscInt_FMT " mu=%g tau=%g kappa=%g\n\n",n,(double)mu,(double)tau,(double)kappa);
62: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
63: Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
64: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
66: /* K is a tridiagonal */
67: MatCreate(PETSC_COMM_WORLD,&K);
68: MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
69: MatSetFromOptions(K);
70: MatSetUp(K);
71: MatGetOwnershipRange(K,&Istart,&Iend);
72: for (i=Istart;i<Iend;i++) {
73: if (i>0) MatSetValue(K,i,i-1,-kappa,INSERT_VALUES);
74: MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES);
75: if (i<n-1) MatSetValue(K,i,i+1,-kappa,INSERT_VALUES);
76: }
77: MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
78: MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);
80: /* C is a tridiagonal */
81: MatCreate(PETSC_COMM_WORLD,&C);
82: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
83: MatSetFromOptions(C);
84: MatSetUp(C);
85: MatGetOwnershipRange(C,&Istart,&Iend);
86: for (i=Istart;i<Iend;i++) {
87: if (i>0) MatSetValue(C,i,i-1,-tau,INSERT_VALUES);
88: MatSetValue(C,i,i,tau*3.0,INSERT_VALUES);
89: if (i<n-1) MatSetValue(C,i,i+1,-tau,INSERT_VALUES);
90: }
91: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
92: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
94: /* M is a diagonal matrix */
95: MatCreate(PETSC_COMM_WORLD,&M);
96: MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
97: MatSetFromOptions(M);
98: MatSetUp(M);
99: MatGetOwnershipRange(M,&Istart,&Iend);
100: for (i=Istart;i<Iend;i++) MatSetValue(M,i,i,mu,INSERT_VALUES);
101: MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
102: MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
104: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
105: Create the eigensolver and set various options
106: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
108: PEPCreate(PETSC_COMM_WORLD,&pep);
109: A[0] = K; A[1] = C; A[2] = M;
110: PEPSetOperators(pep,3,A);
111: PEPSetProblemType(pep,PEP_GENERAL);
112: PEPSetTolerances(pep,PETSC_SMALL,PETSC_DEFAULT);
114: /*
115: Define the region containing the eigenvalues of interest
116: */
117: PEPGetRG(pep,&rg);
118: RGSetType(rg,RGINTERVAL);
119: RGIntervalSetEndpoints(rg,-0.5057,-0.5052,-0.001,0.001);
120: PEPSetTarget(pep,-0.43);
121: PEPSetWhichEigenpairs(pep,PEP_TARGET_MAGNITUDE);
122: PEPGetST(pep,&st);
123: STSetType(st,STSINVERT);
125: /*
126: Set solver options. In particular, we must allocate sufficient
127: storage for all eigenpairs that may converge (ncv). This is
128: application-dependent.
129: */
130: mpd = 40;
131: PEPSetDimensions(pep,2*mpd,3*mpd,mpd);
132: PEPSetTolerances(pep,PETSC_DEFAULT,2000);
133: PetscNew(&ctx);
134: ctx->lastnconv = 0;
135: ctx->nreps = 0;
136: PEPSetStoppingTestFunction(pep,MyStoppingTest,(void*)ctx,NULL);
138: PEPSetFromOptions(pep);
140: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
141: Solve the eigensystem
142: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
144: PEPSolve(pep);
146: /* show detailed info unless -terse option is given by user */
147: PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
148: PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
149: PEPConvergedReasonView(pep,viewer);
150: PetscOptionsHasName(NULL,NULL,"-terse",&terse);
151: if (!terse) PEPErrorView(pep,PEP_ERROR_BACKWARD,viewer);
152: PetscViewerPopFormat(viewer);
154: PEPDestroy(&pep);
155: MatDestroy(&M);
156: MatDestroy(&C);
157: MatDestroy(&K);
158: PetscFree(ctx);
159: SlepcFinalize();
160: return 0;
161: }
163: /*
164: Function for user-defined stopping test.
166: Ignores the value of nev. It only takes into account the number of
167: eigenpairs that have converged in recent outer iterations (restarts);
168: if no new eigenvalues have converged in the last few restarts,
169: we stop the iteration, assuming that no more eigenvalues are present
170: inside the region.
171: */
172: PetscErrorCode MyStoppingTest(PEP pep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,PEPConvergedReason *reason,void *ptr)
173: {
174: CTX_SPRING *ctx = (CTX_SPRING*)ptr;
177: /* check usual termination conditions, but ignoring the case nconv>=nev */
178: PEPStoppingBasic(pep,its,max_it,nconv,PETSC_MAX_INT,reason,NULL);
179: if (*reason==PEP_CONVERGED_ITERATING) {
180: /* check if nconv is the same as before */
181: if (nconv==ctx->lastnconv) ctx->nreps++;
182: else {
183: ctx->lastnconv = nconv;
184: ctx->nreps = 0;
185: }
186: /* check if no eigenvalues converged in last 10 restarts */
187: if (nconv && ctx->nreps>10) *reason = PEP_CONVERGED_USER;
188: }
189: return 0;
190: }
192: /*TEST
194: test:
195: args: -terse
196: suffix: 1
198: TEST*/