Actual source code: test12.c
slepc-3.18.0 2022-10-01
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[] = "Diagonal eigenproblem. Illustrates use of shell preconditioner.\n\n"
12: "The command line options are:\n"
13: " -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n"
14: " -seed <s>, where <s> = seed for random number generation.\n\n";
16: #include <slepceps.h>
18: PetscErrorCode PCApply_User(PC pc,Vec x,Vec y)
19: {
21: VecCopy(x,y);
22: return 0;
23: }
25: int main(int argc,char **argv)
26: {
27: Mat A; /* problem matrix */
28: EPS eps; /* eigenproblem solver context */
29: Vec v0; /* initial vector */
30: PetscRandom rand;
31: PetscReal tol=PETSC_SMALL;
32: PetscInt n=30,i,Istart,Iend,seed=0x12345678;
33: ST st;
34: KSP ksp;
35: PC pc;
38: SlepcInitialize(&argc,&argv,(char*)0,help);
40: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
41: PetscPrintf(PETSC_COMM_WORLD,"\nDiagonal Eigenproblem, n=%" PetscInt_FMT "\n\n",n);
43: MatCreate(PETSC_COMM_WORLD,&A);
44: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
45: MatSetFromOptions(A);
46: MatSetUp(A);
47: MatGetOwnershipRange(A,&Istart,&Iend);
48: for (i=Istart;i<Iend;i++) MatSetValue(A,i,i,i+1,INSERT_VALUES);
49: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
50: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
52: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
53: Solve the eigensystem
54: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
55: EPSCreate(PETSC_COMM_WORLD,&eps);
56: EPSSetOperators(eps,A,NULL);
57: EPSSetProblemType(eps,EPS_HEP);
58: EPSSetTolerances(eps,tol,PETSC_DEFAULT);
59: EPSSetFromOptions(eps);
60: EPSGetST(eps,&st);
61: STGetKSP(st,&ksp);
62: KSPGetPC(ksp,&pc);
63: PCSetType(pc,PCSHELL);
64: PCShellSetApply(pc,PCApply_User);
66: /* set random initial vector */
67: MatCreateVecs(A,&v0,NULL);
68: PetscRandomCreate(PETSC_COMM_WORLD,&rand);
69: PetscRandomSetFromOptions(rand);
70: PetscOptionsGetInt(NULL,NULL,"-seed",&seed,NULL);
71: PetscRandomSetSeed(rand,seed);
72: PetscRandomSeed(rand);
73: VecSetRandom(v0,rand);
74: EPSSetInitialSpace(eps,1,&v0);
75: /* call the solver */
76: EPSSolve(eps);
78: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
79: Display solution and clean up
80: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
81: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
82: EPSDestroy(&eps);
83: MatDestroy(&A);
84: VecDestroy(&v0);
85: PetscRandomDestroy(&rand);
86: SlepcFinalize();
87: return 0;
88: }
90: /*TEST
92: testset:
93: requires: !single
94: output_file: output/test12_1.out
95: test:
96: suffix: 1
97: args: -eps_type {{krylovschur subspace arnoldi gd jd}} -eps_nev 4
98: test:
99: suffix: 1_power
100: args: -eps_type power -eps_max_it 10000 -eps_nev 4
101: test:
102: suffix: 1_gd2
103: args: -eps_type gd -eps_gd_double_expansion -eps_nev 4
105: TEST*/