Actual source code: acoustic_wave_2d.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 acoustic_wave_2d problem is a 2-D version of acoustic_wave_1d, also
30: scaled for real arithmetic.
31: */
33: static char help[] = "NLEVP problem: acoustic_wave_2d.\n\n"
34: "The command line options are:\n"
35: " -m <m>, where <m> = grid size, the matrices have dimension m*(m-1).\n"
36: " -z <z>, where <z> = impedance (default 1.0).\n\n";
38: #include <slepcpep.h>
42: int main(int argc,char **argv)
43: {
44: Mat M,C,K,A[3]; /* problem matrices */
45: PEP pep; /* polynomial eigenproblem solver context */
46: PetscInt m=6,n,II,Istart,Iend,i,j;
47: PetscScalar z=1.0;
48: PetscReal h;
49: char str[50];
52: SlepcInitialize(&argc,&argv,(char*)0,help);
54: PetscOptionsGetInt(NULL,"-m",&m,NULL);
55: if (m<2) SETERRQ(PETSC_COMM_SELF,1,"m must be at least 2");
56: PetscOptionsGetScalar(NULL,"-z",&z,NULL);
57: h = 1.0/m;
58: n = m*(m-1);
59: SlepcSNPrintfScalar(str,50,z,PETSC_FALSE);
60: PetscPrintf(PETSC_COMM_WORLD,"\nAcoustic wave 2-D, n=%D (m=%D), z=%s\n\n",n,m,str);
62: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
63: Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
64: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
66: /* K has a pattern similar to the 2D Laplacian */
67: MatCreate(PETSC_COMM_WORLD,&K);
68: MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,n,n);
69: MatSetFromOptions(K);
70: MatSetUp(K);
71:
72: MatGetOwnershipRange(K,&Istart,&Iend);
73: for (II=Istart;II<Iend;II++) {
74: i = II/m; j = II-i*m;
75: if (i>0) { MatSetValue(K,II,II-m,(j==m-1)?-0.5:-1.0,INSERT_VALUES); }
76: if (i<m-2) { MatSetValue(K,II,II+m,(j==m-1)?-0.5:-1.0,INSERT_VALUES); }
77: if (j>0) { MatSetValue(K,II,II-1,-1.0,INSERT_VALUES); }
78: if (j<m-1) { MatSetValue(K,II,II+1,-1.0,INSERT_VALUES); }
79: MatSetValue(K,II,II,(j==m-1)?2.0:4.0,INSERT_VALUES);
80: }
82: MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
83: MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);
85: /* C is the zero matrix except for a few nonzero elements on the diagonal */
86: MatCreate(PETSC_COMM_WORLD,&C);
87: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,n,n);
88: MatSetFromOptions(C);
89: MatSetUp(C);
91: MatGetOwnershipRange(C,&Istart,&Iend);
92: for (i=Istart;i<Iend;i++) {
93: if (i%m==m-1) {
94: MatSetValue(C,i,i,-2*PETSC_PI*h/z,INSERT_VALUES);
95: }
96: }
97: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
98: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
99:
100: /* M is a diagonal matrix */
101: MatCreate(PETSC_COMM_WORLD,&M);
102: MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,n,n);
103: MatSetFromOptions(M);
104: MatSetUp(M);
106: MatGetOwnershipRange(M,&Istart,&Iend);
107: for (i=Istart;i<Iend;i++) {
108: if (i%m==m-1) {
109: MatSetValue(M,i,i,2*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
110: } else {
111: MatSetValue(M,i,i,4*PETSC_PI*PETSC_PI*h*h,INSERT_VALUES);
112: }
113: }
114: MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
115: MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);
116:
117: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
118: Create the eigensolver and solve the problem
119: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
121: PEPCreate(PETSC_COMM_WORLD,&pep);
122: A[0] = K; A[1] = C; A[2] = M;
123: PEPSetOperators(pep,3,A);
124: PEPSetFromOptions(pep);
125: PEPSolve(pep);
127: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
128: Display solution and clean up
129: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
130:
131: PEPPrintSolution(pep,NULL);
132: PEPDestroy(&pep);
133: MatDestroy(&M);
134: MatDestroy(&C);
135: MatDestroy(&K);
136: SlepcFinalize();
137: return 0;
138: }