Actual source code: test10.c
slepc-3.17.1 2022-04-11
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;
41: SlepcInitialize(&argc,&argv,(char*)0,help);
42: PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
43: PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg);
44: if (!flg) n=m+2;
45: PetscOptionsGetInt(NULL,NULL,"-k",&k,NULL);
46: PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%" PetscInt_FMT " n=%" PetscInt_FMT "\n\n",m,n);
48: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
49: Generate the matrix
50: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
52: MatCreate(PETSC_COMM_WORLD,&A);
53: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n);
54: MatSetFromOptions(A);
55: MatSetUp(A);
56: MatGetOwnershipRange(A,&Istart,&Iend);
57: for (i=Istart;i<Iend;i++) {
58: col[0]=i; col[1]=i+1;
59: if (i<n-1) MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
60: else if (i==n-1) MatSetValue(A,i,col[0],value[0],INSERT_VALUES);
61: }
62: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
63: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
64: MatCreateVecs(A,&v,&u);
66: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
67: Create standalone BV objects to illustrate use of SVDSetBV()
68: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
70: BVCreate(PETSC_COMM_WORLD,&U);
71: PetscObjectSetName((PetscObject)U,"U");
72: BVSetSizesFromVec(U,u,k);
73: BVSetFromOptions(U);
74: BVCreate(PETSC_COMM_WORLD,&V);
75: PetscObjectSetName((PetscObject)V,"V");
76: BVSetSizesFromVec(V,v,k);
77: BVSetFromOptions(V);
79: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
80: Compute singular values
81: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
83: SVDCreate(PETSC_COMM_WORLD,&svd);
84: SVDSetBV(svd,V,U);
85: SVDSetOptionsPrefix(svd,"check_");
86: SVDAppendOptionsPrefix(svd,"myprefix_");
87: SVDGetOptionsPrefix(svd,&prefix);
88: PetscPrintf(PETSC_COMM_WORLD,"SVD prefix is currently: %s\n\n",prefix);
89: PetscObjectSetName((PetscObject)svd,"SVD_solver");
91: SVDSetOperators(svd,A,NULL);
92: SVDSetType(svd,SVDLANCZOS);
93: SVDSetFromOptions(svd);
95: PetscObjectTypeCompare((PetscObject)svd,SVDLANCZOS,&flg);
96: if (flg) {
97: SVDLanczosGetOneSide(svd,&oneside);
98: PetscPrintf(PETSC_COMM_WORLD,"Running Lanczos %s\n\n",oneside?"(onesided)":"");
99: }
100: PetscObjectTypeCompare((PetscObject)svd,SVDTRLANCZOS,&flg);
101: if (flg) {
102: SVDTRLanczosGetOneSide(svd,&oneside);
103: PetscPrintf(PETSC_COMM_WORLD,"Running thick-restart Lanczos %s\n\n",oneside?"(onesided)":"");
104: }
106: SVDSolve(svd);
108: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
109: Display solution and clean up
110: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
111: SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
112: BVDestroy(&U);
113: BVDestroy(&V);
114: VecDestroy(&u);
115: VecDestroy(&v);
116: SVDDestroy(&svd);
117: MatDestroy(&A);
118: SlepcFinalize();
119: return 0;
120: }
122: /*TEST
124: testset:
125: args: -check_myprefix_svd_nsv 3
126: requires: double
127: test:
128: suffix: 1
129: args: -check_myprefix_svd_view_vectors ::ascii_info
130: test:
131: suffix: 2
132: args: -check_myprefix_svd_type trlanczos -check_myprefix_svd_monitor -check_myprefix_svd_view_values ::ascii_matlab
133: filter: sed -e "s/[0-9]\.[0-9]*e[+-]\([0-9]*\)/removed/g"
134: test:
135: suffix: 3
136: args: -m 22 -n 20
138: TEST*/