Actual source code: test9.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[] = "Test DSGHEP.\n\n";
13: #include <slepcds.h>
15: /*
16: Compute the norm of the j-th column of matrix mat in ds
17: */
18: PetscErrorCode ComputeNorm(DS ds,DSMatType mat,PetscInt j,PetscReal *onrm)
19: {
20: PetscScalar *X;
21: PetscReal aux,nrm=0.0;
22: PetscInt i,n,ld;
25: DSGetLeadingDimension(ds,&ld);
26: DSGetDimensions(ds,&n,NULL,NULL,NULL);
27: DSGetArray(ds,mat,&X);
28: for (i=0;i<n;i++) {
29: aux = PetscAbsScalar(X[i+j*ld]);
30: nrm += aux*aux;
31: }
32: DSRestoreArray(ds,mat,&X);
33: *onrm = PetscSqrtReal(nrm);
34: return 0;
35: }
37: int main(int argc,char **argv)
38: {
39: DS ds;
40: SlepcSC sc;
41: PetscReal re;
42: PetscScalar *A,*B,*eig;
43: PetscReal nrm;
44: PetscInt i,j,n=10,ld;
45: PetscViewer viewer;
46: PetscBool verbose;
49: SlepcInitialize(&argc,&argv,(char*)0,help);
50: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
51: PetscPrintf(PETSC_COMM_WORLD,"Solve a System of type GHEP - dimension %" PetscInt_FMT ".\n",n);
52: PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);
54: /* Create DS object */
55: DSCreate(PETSC_COMM_WORLD,&ds);
56: DSSetType(ds,DSGHEP);
57: DSSetFromOptions(ds);
58: ld = n+2; /* test leading dimension larger than n */
59: DSAllocate(ds,ld);
60: DSSetDimensions(ds,n,0,0);
62: /* Set up viewer */
63: PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
64: PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
65: DSView(ds,viewer);
66: PetscViewerPopFormat(viewer);
67: if (verbose) PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
69: /* Fill with a symmetric Toeplitz matrix */
70: DSGetArray(ds,DS_MAT_A,&A);
71: DSGetArray(ds,DS_MAT_B,&B);
72: for (i=0;i<n;i++) A[i+i*ld]=2.0;
73: for (j=1;j<3;j++) {
74: for (i=0;i<n-j;i++) { A[i+(i+j)*ld]=1.0; A[(i+j)+i*ld]=1.0; }
75: }
76: for (j=1;j<3;j++) { A[0+j*ld]=-1.0*(j+2); A[j+0*ld]=-1.0*(j+2); }
77: /* Diagonal matrix */
78: for (i=0;i<n;i++) B[i+i*ld]=0.1*(i+1);
79: DSRestoreArray(ds,DS_MAT_A,&A);
80: DSRestoreArray(ds,DS_MAT_B,&B);
81: DSSetState(ds,DS_STATE_RAW);
82: if (verbose) {
83: PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
84: DSView(ds,viewer);
85: }
87: /* Solve */
88: PetscMalloc1(n,&eig);
89: PetscNew(&sc);
90: sc->comparison = SlepcCompareLargestMagnitude;
91: sc->comparisonctx = NULL;
92: sc->map = NULL;
93: sc->mapobj = NULL;
94: DSSetSlepcSC(ds,sc);
95: DSSolve(ds,eig,NULL);
96: DSSort(ds,eig,NULL,NULL,NULL,NULL);
97: if (verbose) {
98: PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");
99: DSView(ds,viewer);
100: }
102: /* Print eigenvalues */
103: PetscPrintf(PETSC_COMM_WORLD,"Computed eigenvalues =\n");
104: for (i=0;i<n;i++) {
105: re = PetscRealPart(eig[i]);
106: PetscViewerASCIIPrintf(viewer," %.5f\n",(double)re);
107: }
109: /* Eigenvectors */
110: j = 0;
111: DSVectors(ds,DS_MAT_X,&j,NULL); /* all eigenvectors */
112: ComputeNorm(ds,DS_MAT_X,0,&nrm);
113: PetscPrintf(PETSC_COMM_WORLD,"Norm of 1st vector = %.3f\n",(double)nrm);
114: DSVectors(ds,DS_MAT_X,NULL,NULL); /* all eigenvectors */
115: if (verbose) {
116: PetscPrintf(PETSC_COMM_WORLD,"After vectors - - - - - - - - -\n");
117: DSView(ds,viewer);
118: }
120: PetscFree(eig);
121: PetscFree(sc);
122: DSDestroy(&ds);
123: SlepcFinalize();
124: return 0;
125: }
127: /*TEST
129: test:
130: suffix: 1
131: requires: !single
133: TEST*/