Actual source code: test7.c
slepc-3.16.2 2022-02-01
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 DSSVD.\n\n";
13: #include <slepcds.h>
15: int main(int argc,char **argv)
16: {
18: DS ds;
19: SlepcSC sc;
20: PetscReal sigma,rnorm,aux;
21: PetscScalar *A,*U,*w,d;
22: PetscInt i,j,k,n=15,m=10,m1,ld;
23: PetscViewer viewer;
24: PetscBool verbose,extrarow;
26: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
27: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
28: PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
29: k = PetscMin(n,m);
30: PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type SVD - dimension %Dx%D.\n",n,m);
31: PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);
32: PetscOptionsHasName(NULL,NULL,"-extrarow",&extrarow);
34: /* Create DS object */
35: DSCreate(PETSC_COMM_WORLD,&ds);
36: DSSetType(ds,DSSVD);
37: DSSetFromOptions(ds);
38: ld = n+2; /* test leading dimension larger than n */
39: DSAllocate(ds,ld);
40: DSSetDimensions(ds,n,0,0);
41: DSSVDSetDimensions(ds,m);
42: DSSVDGetDimensions(ds,&m1);
43: if (m1!=m) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_PLIB,"Inconsistent dimension value");
44: DSSetExtraRow(ds,extrarow);
46: /* Set up viewer */
47: PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);
48: PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);
49: DSView(ds,viewer);
50: PetscViewerPopFormat(viewer);
52: /* Fill with a rectangular Toeplitz matrix */
53: DSGetArray(ds,DS_MAT_A,&A);
54: for (i=0;i<k;i++) A[i+i*ld]=1.0;
55: for (j=1;j<3;j++) {
56: for (i=0;i<n-j;i++) { if ((i+j)<m) A[i+(i+j)*ld]=(PetscScalar)(j+1); }
57: }
58: for (j=1;j<n/2;j++) {
59: for (i=0;i<n-j;i++) { if ((i+j)<n && i<m) A[(i+j)+i*ld]=-1.0; }
60: }
61: if (extrarow) { A[n-2+m*ld]=1.0; A[n-1+m*ld]=1.0; } /* really an extra column */
62: DSRestoreArray(ds,DS_MAT_A,&A);
63: DSSetState(ds,DS_STATE_RAW);
64: if (verbose) {
65: PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);
66: PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");
67: }
68: DSView(ds,viewer);
70: /* Solve */
71: PetscMalloc1(k,&w);
72: DSGetSlepcSC(ds,&sc);
73: sc->comparison = SlepcCompareLargestReal;
74: sc->comparisonctx = NULL;
75: sc->map = NULL;
76: sc->mapobj = NULL;
77: DSSolve(ds,w,NULL);
78: DSSort(ds,w,NULL,NULL,NULL,NULL);
79: if (extrarow) { DSUpdateExtraRow(ds); }
80: if (verbose) {
81: PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");
82: DSView(ds,viewer);
83: }
85: /* Print singular values */
86: PetscPrintf(PETSC_COMM_WORLD,"Computed singular values =\n");
87: for (i=0;i<k;i++) {
88: sigma = PetscRealPart(w[i]);
89: PetscViewerASCIIPrintf(viewer," %.5f\n",(double)sigma);
90: }
92: if (extrarow) {
93: /* Check that extra column is correct */
94: DSGetArray(ds,DS_MAT_A,&A);
95: DSGetArray(ds,DS_MAT_U,&U);
96: d = 0.0;
97: for (i=0;i<n;i++) d += A[i+m*ld]-U[n-2+i*ld]-U[n-1+i*ld];
98: if (PetscAbsScalar(d)>10*PETSC_MACHINE_EPSILON) {
99: PetscPrintf(PETSC_COMM_WORLD,"Warning: there is a mismatch in the extra row of %g\n",(double)PetscAbsScalar(d));
100: }
101: DSRestoreArray(ds,DS_MAT_A,&A);
102: DSRestoreArray(ds,DS_MAT_U,&U);
103: }
105: /* Singular vectors */
106: DSVectors(ds,DS_MAT_U,NULL,NULL); /* all singular vectors */
107: j = 0;
108: rnorm = 0.0;
109: DSGetArray(ds,DS_MAT_U,&U);
110: for (i=0;i<n;i++) {
111: aux = PetscAbsScalar(U[i+j*ld]);
112: rnorm += aux*aux;
113: }
114: DSRestoreArray(ds,DS_MAT_U,&U);
115: rnorm = PetscSqrtReal(rnorm);
116: PetscPrintf(PETSC_COMM_WORLD,"Norm of 1st U vector = %.3f\n",(double)rnorm);
118: PetscFree(w);
119: DSDestroy(&ds);
120: SlepcFinalize();
121: return ierr;
122: }
124: /*TEST
126: test:
127: suffix: 1
128: requires: !single
130: test:
131: suffix: 2
132: args: -extrarow
133: requires: !single
135: TEST*/