Actual source code: test40.c
slepc-3.15.0 2021-03-31
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2021, 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[] = "Test two-sided Krylov-Schur without calling EPSSetFromOptions (based on ex5.c).\n\n"
12: "The command line options are:\n"
13: " -m <m>, where <m> = number of grid subdivisions in each dimension.\n\n";
15: #include <slepceps.h>
17: /*
18: User-defined routines
19: */
20: PetscErrorCode MatMarkovModel(PetscInt m,Mat A);
22: int main(int argc,char **argv)
23: {
24: Mat A; /* operator matrix */
25: EPS eps; /* eigenproblem solver context */
26: PetscReal tol=1000*PETSC_MACHINE_EPSILON;
27: PetscInt N,m=15,nev;
30: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
32: PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
33: N = m*(m+1)/2;
34: PetscPrintf(PETSC_COMM_WORLD,"\nMarkov Model, N=%D (m=%D)\n\n",N,m);
36: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
37: Compute the operator matrix that defines the eigensystem, Ax=kx
38: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
40: MatCreate(PETSC_COMM_WORLD,&A);
41: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);
42: MatSetFromOptions(A);
43: MatSetUp(A);
44: MatMarkovModel(m,A);
46: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
47: Create the eigensolver and set various options
48: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
50: EPSCreate(PETSC_COMM_WORLD,&eps);
51: EPSSetOperators(eps,A,NULL);
52: EPSSetProblemType(eps,EPS_NHEP);
53: EPSSetTolerances(eps,tol,PETSC_DEFAULT);
54: EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);
55: EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
56: EPSSetTwoSided(eps,PETSC_TRUE);
58: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
59: Solve the eigensystem
60: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
62: EPSSolve(eps);
63: EPSGetDimensions(eps,&nev,NULL,NULL);
64: PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);
66: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
67: Display solution and clean up
68: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
70: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
71: EPSDestroy(&eps);
72: MatDestroy(&A);
73: SlepcFinalize();
74: return ierr;
75: }
77: PetscErrorCode MatMarkovModel(PetscInt m,Mat A)
78: {
79: const PetscReal cst = 0.5/(PetscReal)(m-1);
80: PetscReal pd,pu;
81: PetscInt Istart,Iend,i,j,jmax,ix=0;
82: PetscErrorCode ierr;
85: MatGetOwnershipRange(A,&Istart,&Iend);
86: for (i=1;i<=m;i++) {
87: jmax = m-i+1;
88: for (j=1;j<=jmax;j++) {
89: ix = ix + 1;
90: if (ix-1<Istart || ix>Iend) continue; /* compute only owned rows */
91: if (j!=jmax) {
92: pd = cst*(PetscReal)(i+j-1);
93: /* north */
94: if (i==1) {
95: MatSetValue(A,ix-1,ix,2*pd,INSERT_VALUES);
96: } else {
97: MatSetValue(A,ix-1,ix,pd,INSERT_VALUES);
98: }
99: /* east */
100: if (j==1) {
101: MatSetValue(A,ix-1,ix+jmax-1,2*pd,INSERT_VALUES);
102: } else {
103: MatSetValue(A,ix-1,ix+jmax-1,pd,INSERT_VALUES);
104: }
105: }
106: /* south */
107: pu = 0.5 - cst*(PetscReal)(i+j-3);
108: if (j>1) {
109: MatSetValue(A,ix-1,ix-2,pu,INSERT_VALUES);
110: }
111: /* west */
112: if (i>1) {
113: MatSetValue(A,ix-1,ix-jmax-2,pu,INSERT_VALUES);
114: }
115: }
116: }
117: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
118: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
119: return(0);
120: }
122: /*TEST
124: test:
125: requires: !single
127: TEST*/