Actual source code: spring.c
slepc-3.11.2 2019-07-30
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2019, 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: This example implements one of the problems found at
12: NLEVP: A Collection of Nonlinear Eigenvalue Problems,
13: The University of Manchester.
14: The details of the collection can be found at:
15: [1] T. Betcke et al., "NLEVP: A Collection of Nonlinear Eigenvalue
16: Problems", ACM Trans. Math. Software 39(2), Article 7, 2013.
18: The spring problem is a QEP from the finite element model of a damped
19: mass-spring system. This implementation supports only scalar parameters,
20: that is all masses, dampers and springs have the same constants.
21: Furthermore, this implementation does not consider different constants
22: for dampers and springs connecting adjacent masses or masses to the ground.
23: */
25: static char help[] = "FEM model of a damped mass-spring system.\n\n"
26: "The command line options are:\n"
27: " -n <n> ... dimension of the matrices.\n"
28: " -mu <value> ... mass (default 1).\n"
29: " -tau <value> ... damping constant of the dampers (default 10).\n"
30: " -kappa <value> ... damping constant of the springs (default 5).\n\n";
32: #include <slepcpep.h>
34: int main(int argc,char **argv)
35: {
36: Mat M,C,K,A[3]; /* problem matrices */
37: PEP pep; /* polynomial eigenproblem solver context */
38: PetscInt n=5,Istart,Iend,i;
39: PetscReal mu=1,tau=10,kappa=5;
40: PetscBool terse;
43: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
45: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
46: PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL);
47: PetscOptionsGetReal(NULL,NULL,"-tau",&tau,NULL);
48: PetscOptionsGetReal(NULL,NULL,"-kappa",&kappa,NULL);
49: 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);
51: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
52: Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
53: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
55: /* K is a tridiagonal */
56: MatCreate(PETSC_COMM_WORLD,&K);
57: MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
58: MatSetFromOptions(K);
59: MatSetUp(K);
61: MatGetOwnershipRange(K,&Istart,&Iend);
62: for (i=Istart;i<Iend;i++) {
63: if (i>0) {
64: MatSetValue(K,i,i-1,-kappa,INSERT_VALUES);
65: }
66: MatSetValue(K,i,i,kappa*3.0,INSERT_VALUES);
67: if (i<n-1) {
68: MatSetValue(K,i,i+1,-kappa,INSERT_VALUES);
69: }
70: }
72: MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
73: MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);
75: /* C is a tridiagonal */
76: MatCreate(PETSC_COMM_WORLD,&C);
77: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
78: MatSetFromOptions(C);
79: MatSetUp(C);
81: MatGetOwnershipRange(C,&Istart,&Iend);
82: for (i=Istart;i<Iend;i++) {
83: if (i>0) {
84: MatSetValue(C,i,i-1,-tau,INSERT_VALUES);
85: }
86: MatSetValue(C,i,i,tau*3.0,INSERT_VALUES);
87: if (i<n-1) {
88: MatSetValue(C,i,i+1,-tau,INSERT_VALUES);
89: }
90: }
92: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
93: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
95: /* M is a diagonal matrix */
96: MatCreate(PETSC_COMM_WORLD,&M);
97: MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
98: MatSetFromOptions(M);
99: MatSetUp(M);
100: MatGetOwnershipRange(M,&Istart,&Iend);
101: for (i=Istart;i<Iend;i++) {
102: MatSetValue(M,i,i,mu,INSERT_VALUES);
103: }
104: MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
105: MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
107: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
108: Create the eigensolver and solve the problem
109: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
111: PEPCreate(PETSC_COMM_WORLD,&pep);
112: A[0] = K; A[1] = C; A[2] = M;
113: PEPSetOperators(pep,3,A);
114: PEPSetFromOptions(pep);
115: PEPSolve(pep);
117: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
118: Display solution and clean up
119: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
121: /* show detailed info unless -terse option is given by user */
122: PetscOptionsHasName(NULL,NULL,"-terse",&terse);
123: if (terse) {
124: PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
125: } else {
126: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
127: PEPReasonView(pep,PETSC_VIEWER_STDOUT_WORLD);
128: PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD);
129: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
130: }
131: PEPDestroy(&pep);
132: MatDestroy(&M);
133: MatDestroy(&C);
134: MatDestroy(&K);
135: SlepcFinalize();
136: return ierr;
137: }
139: /*TEST
141: testset:
142: args: -pep_nev 4 -n 24 -pep_ncv 18 -pep_target -.5 -st_type sinvert -pep_scale diagonal -terse
143: requires: !single
144: output_file: output/spring_1.out
145: test:
146: suffix: 1
147: args: -pep_type {{toar linear}} -pep_conv_norm
148: test:
149: suffix: 1_stoar
150: args: -pep_type stoar -pep_hermitian -pep_conv_rel
151: test:
152: suffix: 1_qarnoldi
153: args: -pep_type qarnoldi -pep_conv_rel
155: test:
156: suffix: 2
157: args: -pep_type jd -pep_jd_minimality_index 1 -pep_nev 4 -n 24 -pep_ncv 18 -pep_target -50 -terse
158: requires: !single
160: test:
161: suffix: 3
162: args: -n 300 -pep_hermitian -pep_interval -10.1,-9.5 -pep_type stoar -st_type sinvert -st_pc_type cholesky -terse
163: requires: !single
165: test:
166: suffix: 4
167: args: -n 300 -pep_hyperbolic -pep_interval -9.6,-.527 -pep_type stoar -st_type sinvert -st_pc_type cholesky -terse
168: requires: !single
170: test:
171: suffix: 5
172: args: -n 300 -pep_hyperbolic -pep_interval -.506,-.3 -pep_type stoar -st_type sinvert -st_pc_type cholesky -pep_stoar_nev 10 -terse
173: requires: !single !complex
175: test:
176: suffix: 6
177: args: -n 24 -pep_ncv 18 -pep_target -.5 -terse -pep_type jd -pep_jd_restart .6 -pep_jd_fix .001
178: requires: !single
179: TEST*/