Actual source code: test12.c
slepc-3.16.2 2022-02-01
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2021, 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: */
11: static char help[] = "Illustrates region filtering in PEP (based on spring).\n"
12: "The command line options are:\n"
13: " -n <n> ... number of grid subdivisions.\n"
14: " -mu <value> ... mass (default 1).\n"
15: " -tau <value> ... damping constant of the dampers (default 10).\n"
16: " -kappa <value> ... damping constant of the springs (default 5).\n\n";
18: #include <slepcpep.h>
20: int main(int argc,char **argv)
21: {
22: Mat M,C,K,A[3]; /* problem matrices */
23: PEP pep; /* polynomial eigenproblem solver context */
24: RG rg;
25: PetscInt n=30,Istart,Iend,i;
26: PetscReal mu=1.0,tau=10.0,kappa=5.0;
29: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
31: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
32: PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL);
33: PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL);
34: PetscOptionsGetReal(NULL,NULL,"-kappa",&kappa,NULL);
35: PetscPrintf(PETSC_COMM_WORLD,"\nDamped mass-spring system, n=%D mu=%g tau=%g kappa=%g\n\n",n,(double)mu,(double)tau,(double)kappa);
37: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
38: Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
39: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
41: /* K is a tridiagonal */
42: MatCreate(PETSC_COMM_WORLD,&K);
43: MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
44: MatSetFromOptions(K);
45: MatSetUp(K);
47: MatGetOwnershipRange(K,&Istart,&Iend);
48: for (i=Istart;i<Iend;i++) {
49: if (i>0) {
50: MatSetValue(K,i,i-1,-kappa,INSERT_VALUES);
51: }
52: MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES);
53: if (i<n-1) {
54: MatSetValue(K,i,i+1,-kappa,INSERT_VALUES);
55: }
56: }
58: MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
59: MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);
61: /* C is a tridiagonal */
62: MatCreate(PETSC_COMM_WORLD,&C);
63: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
64: MatSetFromOptions(C);
65: MatSetUp(C);
67: MatGetOwnershipRange(C,&Istart,&Iend);
68: for (i=Istart;i<Iend;i++) {
69: if (i>0) {
70: MatSetValue(C,i,i-1,-tau,INSERT_VALUES);
71: }
72: MatSetValue(C,i,i,tau*3.0,INSERT_VALUES);
73: if (i<n-1) {
74: MatSetValue(C,i,i+1,-tau,INSERT_VALUES);
75: }
76: }
78: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
79: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
81: /* M is a diagonal matrix */
82: MatCreate(PETSC_COMM_WORLD,&M);
83: MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
84: MatSetFromOptions(M);
85: MatSetUp(M);
86: MatGetOwnershipRange(M,&Istart,&Iend);
87: for (i=Istart;i<Iend;i++) {
88: MatSetValue(M,i,i,mu,INSERT_VALUES);
89: }
90: MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
91: MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
93: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
94: Create a region for filtering
95: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
97: RGCreate(PETSC_COMM_WORLD,&rg);
98: RGSetType(rg,RGINTERVAL);
99: #if defined(PETSC_USE_COMPLEX)
100: RGIntervalSetEndpoints(rg,-47.0,-35.0,-0.001,0.001);
101: #else
102: RGIntervalSetEndpoints(rg,-47.0,-35.0,-0.0,0.0);
103: #endif
105: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
106: Create the eigensolver and solve the problem
107: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
109: PEPCreate(PETSC_COMM_WORLD,&pep);
110: PEPSetRG(pep,rg);
111: A[0] = K; A[1] = C; A[2] = M;
112: PEPSetOperators(pep,3,A);
113: PEPSetTolerances(pep,PETSC_SMALL,PETSC_DEFAULT);
114: PEPSetFromOptions(pep);
115: PEPSolve(pep);
117: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
118: Display solution and clean up
119: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
121: PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
122: PEPDestroy(&pep);
123: MatDestroy(&M);
124: MatDestroy(&C);
125: MatDestroy(&K);
126: RGDestroy(&rg);
127: SlepcFinalize();
128: return ierr;
129: }
131: /*TEST
133: test:
134: args: -pep_nev 8 -pep_type {{toar linear qarnoldi}}
135: suffix: 1
136: requires: !single
137: output_file: output/test12_1.out
139: TEST*/