Actual source code: test12.c
slepc-3.18.2 2023-01-26
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: */
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);
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=%" PetscInt_FMT " 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) MatSetValue(K,i,i-1,-kappa,INSERT_VALUES);
50: MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES);
51: if (i<n-1) MatSetValue(K,i,i+1,-kappa,INSERT_VALUES);
52: }
54: MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
55: MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);
57: /* C is a tridiagonal */
58: MatCreate(PETSC_COMM_WORLD,&C);
59: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
60: MatSetFromOptions(C);
61: MatSetUp(C);
63: MatGetOwnershipRange(C,&Istart,&Iend);
64: for (i=Istart;i<Iend;i++) {
65: if (i>0) MatSetValue(C,i,i-1,-tau,INSERT_VALUES);
66: MatSetValue(C,i,i,tau*3.0,INSERT_VALUES);
67: if (i<n-1) MatSetValue(C,i,i+1,-tau,INSERT_VALUES);
68: }
70: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
71: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
73: /* M is a diagonal matrix */
74: MatCreate(PETSC_COMM_WORLD,&M);
75: MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
76: MatSetFromOptions(M);
77: MatSetUp(M);
78: MatGetOwnershipRange(M,&Istart,&Iend);
79: for (i=Istart;i<Iend;i++) MatSetValue(M,i,i,mu,INSERT_VALUES);
80: MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
81: MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
83: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
84: Create a region for filtering
85: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
87: RGCreate(PETSC_COMM_WORLD,&rg);
88: RGSetType(rg,RGINTERVAL);
89: #if defined(PETSC_USE_COMPLEX)
90: RGIntervalSetEndpoints(rg,-47.0,-35.0,-0.001,0.001);
91: #else
92: RGIntervalSetEndpoints(rg,-47.0,-35.0,-0.0,0.0);
93: #endif
95: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
96: Create the eigensolver and solve the problem
97: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
99: PEPCreate(PETSC_COMM_WORLD,&pep);
100: PEPSetRG(pep,rg);
101: A[0] = K; A[1] = C; A[2] = M;
102: PEPSetOperators(pep,3,A);
103: PEPSetTolerances(pep,PETSC_SMALL,PETSC_DEFAULT);
104: PEPSetFromOptions(pep);
105: PEPSolve(pep);
107: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
108: Display solution and clean up
109: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
111: PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
112: PEPDestroy(&pep);
113: MatDestroy(&M);
114: MatDestroy(&C);
115: MatDestroy(&K);
116: RGDestroy(&rg);
117: SlepcFinalize();
118: return 0;
119: }
121: /*TEST
123: test:
124: args: -pep_nev 8 -pep_type {{toar linear qarnoldi}}
125: suffix: 1
126: requires: !single
127: output_file: output/test12_1.out
129: TEST*/