Actual source code: test2.c
slepc-3.9.2 2018-07-02
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2018, 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[] = "Tests multiple calls to EPSSolve with the same matrix.\n\n";
13: #include <slepceps.h>
15: int main(int argc,char **argv)
16: {
17: Mat A; /* problem matrix */
18: EPS eps; /* eigenproblem solver context */
19: ST st;
20: PetscReal tol=PetscMax(1000*PETSC_MACHINE_EPSILON,1e-9);
21: PetscInt n=30,i,Istart,Iend;
22: PetscBool flg;
24: EPSLanczosReorthogType reorth;
26: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
28: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
29: PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%D\n\n",n);
31: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
32: Compute the operator matrix that defines the eigensystem, Ax=kx
33: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
35: MatCreate(PETSC_COMM_WORLD,&A);
36: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
37: MatSetFromOptions(A);
38: MatSetUp(A);
40: MatGetOwnershipRange(A,&Istart,&Iend);
41: for (i=Istart;i<Iend;i++) {
42: if (i>0) { MatSetValue(A,i,i-1,-1.0,INSERT_VALUES); }
43: if (i<n-1) { MatSetValue(A,i,i+1,-1.0,INSERT_VALUES); }
44: MatSetValue(A,i,i,2.0,INSERT_VALUES);
45: }
46: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
47: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
49: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
50: Create the eigensolver
51: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
52: EPSCreate(PETSC_COMM_WORLD,&eps);
53: EPSSetOperators(eps,A,NULL);
54: EPSSetProblemType(eps,EPS_HEP);
55: EPSSetTolerances(eps,tol,PETSC_DEFAULT);
56: EPSSetFromOptions(eps);
58: /* illustrate how to extract parameters from specific solver types */
59: PetscObjectTypeCompare((PetscObject)eps,EPSLANCZOS,&flg);
60: if (flg) {
61: EPSLanczosGetReorthog(eps,&reorth);
62: PetscPrintf(PETSC_COMM_WORLD,"Reorthogonalization type used in Lanczos: %s\n",EPSLanczosReorthogTypes[reorth]);
63: }
65: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
66: Solve for largest eigenvalues
67: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
68: EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
69: EPSSolve(eps);
70: PetscPrintf(PETSC_COMM_WORLD," - - - Largest eigenvalues - - -\n");
71: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
73: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
74: Solve for smallest eigenvalues
75: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
76: EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
77: EPSSolve(eps);
78: PetscPrintf(PETSC_COMM_WORLD," - - - Smallest eigenvalues - - -\n");
79: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
81: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
82: Solve for interior eigenvalues (target=2.1)
83: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
84: EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
85: EPSSetTarget(eps,2.1);
86: PetscObjectTypeCompare((PetscObject)eps,EPSLANCZOS,&flg);
87: if (flg) {
88: EPSGetST(eps,&st);
89: STSetType(st,STSINVERT);
90: } else {
91: PetscObjectTypeCompare((PetscObject)eps,EPSKRYLOVSCHUR,&flg);
92: if (!flg) {
93: PetscObjectTypeCompare((PetscObject)eps,EPSARNOLDI,&flg);
94: }
95: if (flg) {
96: EPSSetExtraction(eps,EPS_HARMONIC);
97: }
98: }
99: EPSSolve(eps);
100: PetscPrintf(PETSC_COMM_WORLD," - - - Interior eigenvalues - - -\n");
101: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
103: EPSDestroy(&eps);
104: MatDestroy(&A);
105: SlepcFinalize();
106: return ierr;
107: }