Actual source code: test10.c
slepc-3.15.1 2021-05-28
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[] = "Lanczos SVD. Also illustrates the use of SVDSetBV().\n\n"
12: "The command line options are:\n"
13: " -m <m>, where <m> = matrix rows.\n"
14: " -n <n>, where <n> = matrix columns (defaults to m+2).\n\n";
16: #include <slepcsvd.h>
18: /*
19: This example computes the singular values of a rectangular bidiagonal matrix
21: | 1 2 |
22: | 1 2 |
23: | 1 2 |
24: A = | . . |
25: | . . |
26: | 1 2 |
27: | 1 2 |
28: */
30: int main(int argc,char **argv)
31: {
32: Mat A;
33: SVD svd;
34: PetscInt m=20,n,Istart,Iend,i,k=6,col[2];
35: PetscScalar value[] = { 1, 2 };
36: PetscBool flg,oneside=PETSC_FALSE;
37: const char *prefix;
38: BV U,V;
39: Vec u,v;
42: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
43: PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
44: PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg);
45: if (!flg) n=m+2;
46: PetscOptionsGetInt(NULL,NULL,"-k",&k,NULL);
47: PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%D n=%D\n\n",m,n);
49: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
50: Generate the matrix
51: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
53: MatCreate(PETSC_COMM_WORLD,&A);
54: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n);
55: MatSetFromOptions(A);
56: MatSetUp(A);
57: MatGetOwnershipRange(A,&Istart,&Iend);
58: for (i=Istart;i<Iend;i++) {
59: col[0]=i; col[1]=i+1;
60: if (i<n-1) {
61: MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
62: } else if (i==n-1) {
63: MatSetValue(A,i,col[0],value[0],INSERT_VALUES);
64: }
65: }
66: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
67: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
68: MatCreateVecs(A,&v,&u);
70: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
71: Create standalone BV objects to illustrate use of SVDSetBV()
72: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
74: BVCreate(PETSC_COMM_WORLD,&U);
75: PetscObjectSetName((PetscObject)U,"U");
76: BVSetSizesFromVec(U,u,k);
77: BVSetFromOptions(U);
78: BVCreate(PETSC_COMM_WORLD,&V);
79: PetscObjectSetName((PetscObject)V,"V");
80: BVSetSizesFromVec(V,v,k);
81: BVSetFromOptions(V);
83: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
84: Compute singular values
85: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
87: SVDCreate(PETSC_COMM_WORLD,&svd);
88: SVDSetBV(svd,V,U);
89: SVDSetOptionsPrefix(svd,"check_");
90: SVDAppendOptionsPrefix(svd,"myprefix_");
91: SVDGetOptionsPrefix(svd,&prefix);
92: PetscPrintf(PETSC_COMM_WORLD,"SVD prefix is currently: %s\n\n",prefix);
93: PetscObjectSetName((PetscObject)svd,"SVD_solver");
95: SVDSetOperators(svd,A,NULL);
96: SVDSetType(svd,SVDLANCZOS);
97: SVDSetFromOptions(svd);
99: PetscObjectTypeCompare((PetscObject)svd,SVDLANCZOS,&flg);
100: if (flg) {
101: SVDLanczosGetOneSide(svd,&oneside);
102: PetscPrintf(PETSC_COMM_WORLD,"Running Lanczos %s\n\n",oneside?"(onesided)":"");
103: }
104: PetscObjectTypeCompare((PetscObject)svd,SVDTRLANCZOS,&flg);
105: if (flg) {
106: SVDTRLanczosGetOneSide(svd,&oneside);
107: PetscPrintf(PETSC_COMM_WORLD,"Running thick-restart Lanczos %s\n\n",oneside?"(onesided)":"");
108: }
110: SVDSolve(svd);
112: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
113: Display solution and clean up
114: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
115: SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
116: BVDestroy(&U);
117: BVDestroy(&V);
118: VecDestroy(&u);
119: VecDestroy(&v);
120: SVDDestroy(&svd);
121: MatDestroy(&A);
122: SlepcFinalize();
123: return ierr;
124: }
126: /*TEST
128: testset:
129: args: -check_myprefix_svd_nsv 3
130: requires: double
131: test:
132: suffix: 1
133: args: -check_myprefix_svd_view_vectors ::ascii_info
134: test:
135: suffix: 2
136: args: -check_myprefix_svd_type trlanczos -check_myprefix_svd_monitor -check_myprefix_svd_view_values ::ascii_matlab
137: filter: sed -e "s/[0-9]\.[0-9]*e[+-]\([0-9]*\)/removed/g"
138: test:
139: suffix: 3
140: args: -m 22 -n 20
142: TEST*/