Actual source code: test10.c
slepc-3.18.1 2022-11-02
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[] = "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);
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=%" PetscInt_FMT " n=%" PetscInt_FMT "\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) MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
61: else if (i==n-1) MatSetValue(A,i,col[0],value[0],INSERT_VALUES);
62: }
63: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
64: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
65: MatCreateVecs(A,&v,&u);
67: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
68: Create standalone BV objects to illustrate use of SVDSetBV()
69: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
71: BVCreate(PETSC_COMM_WORLD,&U);
72: PetscObjectSetName((PetscObject)U,"U");
73: BVSetSizesFromVec(U,u,k);
74: BVSetFromOptions(U);
75: BVCreate(PETSC_COMM_WORLD,&V);
76: PetscObjectSetName((PetscObject)V,"V");
77: BVSetSizesFromVec(V,v,k);
78: BVSetFromOptions(V);
80: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
81: Compute singular values
82: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
84: SVDCreate(PETSC_COMM_WORLD,&svd);
85: SVDSetBV(svd,V,U);
86: SVDSetOptionsPrefix(svd,"check_");
87: SVDAppendOptionsPrefix(svd,"myprefix_");
88: SVDGetOptionsPrefix(svd,&prefix);
89: PetscPrintf(PETSC_COMM_WORLD,"SVD prefix is currently: %s\n\n",prefix);
90: PetscObjectSetName((PetscObject)svd,"SVD_solver");
92: SVDSetOperators(svd,A,NULL);
93: SVDSetType(svd,SVDLANCZOS);
94: SVDSetFromOptions(svd);
96: PetscObjectTypeCompare((PetscObject)svd,SVDLANCZOS,&flg);
97: if (flg) {
98: SVDLanczosGetOneSide(svd,&oneside);
99: PetscPrintf(PETSC_COMM_WORLD,"Running Lanczos %s\n\n",oneside?"(onesided)":"");
100: }
101: PetscObjectTypeCompare((PetscObject)svd,SVDTRLANCZOS,&flg);
102: if (flg) {
103: SVDTRLanczosGetOneSide(svd,&oneside);
104: PetscPrintf(PETSC_COMM_WORLD,"Running thick-restart Lanczos %s\n\n",oneside?"(onesided)":"");
105: }
107: SVDSolve(svd);
109: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
110: Display solution and clean up
111: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
112: SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
113: BVDestroy(&U);
114: BVDestroy(&V);
115: VecDestroy(&u);
116: VecDestroy(&v);
117: SVDDestroy(&svd);
118: MatDestroy(&A);
119: SlepcFinalize();
120: return 0;
121: }
123: /*TEST
125: testset:
126: args: -check_myprefix_svd_nsv 3
127: requires: double
128: test:
129: suffix: 1
130: args: -check_myprefix_svd_view_vectors ::ascii_info
131: test:
132: suffix: 2
133: args: -check_myprefix_svd_type trlanczos -check_myprefix_svd_monitor -check_myprefix_svd_view_values ::ascii_matlab
134: filter: sed -e "s/[0-9]\.[0-9]*e[+-]\([0-9]*\)/removed/g"
135: test:
136: suffix: 3
137: args: -m 22 -n 20
139: TEST*/