Line data Source code
1 : /*
2 : - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3 : SLEPc - Scalable Library for Eigenvalue Problem Computations
4 : Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
5 :
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].
13 :
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 : */
21 :
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";
28 :
29 : #include <slepcpep.h>
30 :
31 : /*
32 : User-defined routines
33 : */
34 : PetscErrorCode MyStoppingTest(PEP,PetscInt,PetscInt,PetscInt,PetscInt,PEPConvergedReason*,void*);
35 :
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;
40 :
41 1 : int main(int argc,char **argv)
42 : {
43 1 : Mat M,C,K,A[3]; /* problem matrices */
44 1 : PEP pep; /* polynomial eigenproblem solver context */
45 1 : RG rg; /* region object */
46 1 : ST st;
47 1 : CTX_SPRING *ctx;
48 1 : PetscBool terse;
49 1 : PetscViewer viewer;
50 1 : PetscInt n=30,Istart,Iend,i,mpd;
51 1 : PetscReal mu=1.0,tau=10.0,kappa=5.0;
52 :
53 1 : PetscFunctionBeginUser;
54 1 : PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
55 :
56 1 : PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
57 1 : PetscCall(PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL));
58 1 : PetscCall(PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL));
59 1 : PetscCall(PetscOptionsGetReal(NULL,NULL,"-kappa",&kappa,NULL));
60 1 : PetscCall(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));
61 :
62 : /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
63 : Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
64 : - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
65 :
66 : /* K is a tridiagonal */
67 1 : PetscCall(MatCreate(PETSC_COMM_WORLD,&K));
68 1 : PetscCall(MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n));
69 1 : PetscCall(MatSetFromOptions(K));
70 1 : PetscCall(MatGetOwnershipRange(K,&Istart,&Iend));
71 31 : for (i=Istart;i<Iend;i++) {
72 30 : if (i>0) PetscCall(MatSetValue(K,i,i-1,-kappa,INSERT_VALUES));
73 30 : PetscCall(MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES));
74 30 : if (i<n-1) PetscCall(MatSetValue(K,i,i+1,-kappa,INSERT_VALUES));
75 : }
76 1 : PetscCall(MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY));
77 1 : PetscCall(MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY));
78 :
79 : /* C is a tridiagonal */
80 1 : PetscCall(MatCreate(PETSC_COMM_WORLD,&C));
81 1 : PetscCall(MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n));
82 1 : PetscCall(MatSetFromOptions(C));
83 1 : PetscCall(MatGetOwnershipRange(C,&Istart,&Iend));
84 31 : for (i=Istart;i<Iend;i++) {
85 30 : if (i>0) PetscCall(MatSetValue(C,i,i-1,-tau,INSERT_VALUES));
86 30 : PetscCall(MatSetValue(C,i,i,tau*3.0,INSERT_VALUES));
87 30 : if (i<n-1) PetscCall(MatSetValue(C,i,i+1,-tau,INSERT_VALUES));
88 : }
89 1 : PetscCall(MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY));
90 1 : PetscCall(MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY));
91 :
92 : /* M is a diagonal matrix */
93 1 : PetscCall(MatCreate(PETSC_COMM_WORLD,&M));
94 1 : PetscCall(MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n));
95 1 : PetscCall(MatSetFromOptions(M));
96 1 : PetscCall(MatGetOwnershipRange(M,&Istart,&Iend));
97 31 : for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(M,i,i,mu,INSERT_VALUES));
98 1 : PetscCall(MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY));
99 1 : PetscCall(MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY));
100 :
101 : /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
102 : Create the eigensolver and set various options
103 : - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
104 :
105 1 : PetscCall(PEPCreate(PETSC_COMM_WORLD,&pep));
106 1 : A[0] = K; A[1] = C; A[2] = M;
107 1 : PetscCall(PEPSetOperators(pep,3,A));
108 1 : PetscCall(PEPSetProblemType(pep,PEP_GENERAL));
109 :
110 : /*
111 : Define the region containing the eigenvalues of interest
112 : */
113 1 : PetscCall(PEPGetRG(pep,&rg));
114 1 : PetscCall(RGSetType(rg,RGINTERVAL));
115 1 : PetscCall(RGIntervalSetEndpoints(rg,-0.5057,-0.5052,-0.001,0.001));
116 1 : PetscCall(PEPSetTarget(pep,-0.43));
117 1 : PetscCall(PEPSetWhichEigenpairs(pep,PEP_TARGET_MAGNITUDE));
118 1 : PetscCall(PEPGetST(pep,&st));
119 1 : PetscCall(STSetType(st,STSINVERT));
120 :
121 : /*
122 : Set solver options. In particular, we must allocate sufficient
123 : storage for all eigenpairs that may converge (ncv). This is
124 : application-dependent.
125 : */
126 1 : mpd = 40;
127 1 : PetscCall(PEPSetDimensions(pep,2*mpd,3*mpd,mpd));
128 1 : PetscCall(PEPSetTolerances(pep,SLEPC_DEFAULT_TOL,2000));
129 1 : PetscCall(PetscNew(&ctx));
130 1 : ctx->lastnconv = 0;
131 1 : ctx->nreps = 0;
132 1 : PetscCall(PEPSetStoppingTestFunction(pep,MyStoppingTest,(void*)ctx,NULL));
133 :
134 1 : PetscCall(PEPSetFromOptions(pep));
135 :
136 : /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
137 : Solve the eigensystem
138 : - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
139 :
140 1 : PetscCall(PEPSolve(pep));
141 :
142 : /* show detailed info unless -terse option is given by user */
143 1 : PetscCall(PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer));
144 1 : PetscCall(PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL));
145 1 : PetscCall(PEPConvergedReasonView(pep,viewer));
146 1 : PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
147 1 : if (!terse) PetscCall(PEPErrorView(pep,PEP_ERROR_BACKWARD,viewer));
148 1 : PetscCall(PetscViewerPopFormat(viewer));
149 :
150 1 : PetscCall(PEPDestroy(&pep));
151 1 : PetscCall(MatDestroy(&M));
152 1 : PetscCall(MatDestroy(&C));
153 1 : PetscCall(MatDestroy(&K));
154 1 : PetscCall(PetscFree(ctx));
155 1 : PetscCall(SlepcFinalize());
156 : return 0;
157 : }
158 :
159 : /*
160 : Function for user-defined stopping test.
161 :
162 : Ignores the value of nev. It only takes into account the number of
163 : eigenpairs that have converged in recent outer iterations (restarts);
164 : if no new eigenvalues have converged in the last few restarts,
165 : we stop the iteration, assuming that no more eigenvalues are present
166 : inside the region.
167 : */
168 13 : PetscErrorCode MyStoppingTest(PEP pep,PetscInt its,PetscInt max_it,PetscInt nconv,PetscInt nev,PEPConvergedReason *reason,void *ptr)
169 : {
170 13 : CTX_SPRING *ctx = (CTX_SPRING*)ptr;
171 :
172 13 : PetscFunctionBeginUser;
173 : /* check usual termination conditions, but ignoring the case nconv>=nev */
174 13 : PetscCall(PEPStoppingBasic(pep,its,max_it,nconv,PETSC_INT_MAX,reason,NULL));
175 13 : if (*reason==PEP_CONVERGED_ITERATING) {
176 : /* check if nconv is the same as before */
177 13 : if (nconv==ctx->lastnconv) ctx->nreps++;
178 : else {
179 1 : ctx->lastnconv = nconv;
180 1 : ctx->nreps = 0;
181 : }
182 : /* check if no eigenvalues converged in last 10 restarts */
183 13 : if (nconv && ctx->nreps>10) *reason = PEP_CONVERGED_USER;
184 : }
185 13 : PetscFunctionReturn(PETSC_SUCCESS);
186 : }
187 :
188 : /*TEST
189 :
190 : test:
191 : args: -terse
192 : requires: !single
193 : suffix: 1
194 :
195 : TEST*/
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