Actual source code: sleeper.c
slepc-3.5.2 2014-10-10
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2014, Universitat Politecnica de Valencia, Spain
6: This file is part of SLEPc.
8: SLEPc is free software: you can redistribute it and/or modify it under the
9: terms of version 3 of the GNU Lesser General Public License as published by
10: the Free Software Foundation.
12: SLEPc is distributed in the hope that it will be useful, but WITHOUT ANY
13: WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14: FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
15: more details.
17: You should have received a copy of the GNU Lesser General Public License
18: along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
19: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
20: */
21: /*
22: This example implements one of the problems found at
23: NLEVP: A Collection of Nonlinear Eigenvalue Problems,
24: The University of Manchester.
25: The details of the collection can be found at:
26: [1] T. Betcke et al., "NLEVP: A Collection of Nonlinear Eigenvalue
27: Problems", ACM Trans. Math. Software 39(2), Article 7, 2013.
29: The sleeper problem is a proportionally damped QEP describing the
30: oscillations of a rail track resting on sleepers.
31: */
33: static char help[] = "NLEVP problem: sleeper.\n\n"
34: "The command line options are:\n"
35: " -n <n>, where <n> = dimension of the matrices.\n\n";
37: #include <slepcpep.h>
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: PetscInt n=10,Istart,Iend,i;
48: SlepcInitialize(&argc,&argv,(char*)0,help);
50: PetscOptionsGetInt(NULL,"-n",&n,NULL);
51: PetscPrintf(PETSC_COMM_WORLD,"\nRailtrack resting on sleepers, n=%D\n\n",n);
53: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
54: Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
55: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
57: /* K is a tridiagonal */
58: MatCreate(PETSC_COMM_WORLD,&K);
59: MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
60: MatSetFromOptions(K);
61: MatSetUp(K);
62:
63: MatGetOwnershipRange(K,&Istart,&Iend);
64: for (i=Istart;i<Iend;i++) {
65: if (i==0) {
66: MatSetValue(K,i,n-1,-3.0,INSERT_VALUES);
67: MatSetValue(K,i,n-2,1.0,INSERT_VALUES);
68: }
69: if (i==1) { MatSetValue(K,i,n-1,1.0,INSERT_VALUES); }
70: if (i>0) { MatSetValue(K,i,i-1,-3.0,INSERT_VALUES); }
71: if (i>1) { MatSetValue(K,i,i-2,1.0,INSERT_VALUES); }
72: MatSetValue(K,i,i,5.0,INSERT_VALUES);
73: if (i==n-1) {
74: MatSetValue(K,i,0,-3.0,INSERT_VALUES);
75: MatSetValue(K,i,1,1.0,INSERT_VALUES);
76: }
77: if (i==n-2) { MatSetValue(K,i,0,1.0,INSERT_VALUES); }
78: if (i<n-1) { MatSetValue(K,i,i+1,-3.0,INSERT_VALUES); }
79: if (i<n-2) { MatSetValue(K,i,i+2,1.0,INSERT_VALUES); }
80: }
82: MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
83: MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);
85: /* C is a circulant matrix */
86: MatCreate(PETSC_COMM_WORLD,&C);
87: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
88: MatSetFromOptions(C);
89: MatSetUp(C);
90:
91: MatGetOwnershipRange(C,&Istart,&Iend);
92: for (i=Istart;i<Iend;i++) {
93: if (i==0) {
94: MatSetValue(C,i,n-1,-4.0,INSERT_VALUES);
95: MatSetValue(C,i,n-2,1.0,INSERT_VALUES);
96: }
97: if (i==1) { MatSetValue(C,i,n-1,1.0,INSERT_VALUES); }
98: if (i>0) { MatSetValue(C,i,i-1,-4.0,INSERT_VALUES); }
99: if (i>1) { MatSetValue(C,i,i-2,1.0,INSERT_VALUES); }
100: MatSetValue(C,i,i,7.0,INSERT_VALUES);
101: if (i==n-1) {
102: MatSetValue(C,i,0,-4.0,INSERT_VALUES);
103: MatSetValue(C,i,1,1.0,INSERT_VALUES);
104: }
105: if (i==n-2) { MatSetValue(C,i,0,1.0,INSERT_VALUES); }
106: if (i<n-1) { MatSetValue(C,i,i+1,-4.0,INSERT_VALUES); }
107: if (i<n-2) { MatSetValue(C,i,i+2,1.0,INSERT_VALUES); }
108: }
110: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
111: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
112:
113: /* M is the identity matrix */
114: MatCreate(PETSC_COMM_WORLD,&M);
115: MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
116: MatSetFromOptions(M);
117: MatSetUp(M);
118: MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
119: MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
120: MatShift(M,1.0);
122: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
123: Create the eigensolver and solve the problem
124: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
126: PEPCreate(PETSC_COMM_WORLD,&pep);
127: A[0] = K; A[1] = C; A[2] = M;
128: PEPSetOperators(pep,3,A);
129: PEPSetFromOptions(pep);
130: PEPSolve(pep);
132: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
133: Display solution and clean up
134: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
135:
136: PEPPrintSolution(pep,NULL);
137: PEPDestroy(&pep);
138: MatDestroy(&M);
139: MatDestroy(&C);
140: MatDestroy(&K);
141: SlepcFinalize();
142: return 0;
143: }