Actual source code: test6.c
slepc-3.17.0 2022-03-31
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[] = "SVD via the cross-product matrix with a user-provided EPS.\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: EPS eps;
35: ST st;
36: KSP ksp;
37: PC pc;
38: PetscInt m=20,n,Istart,Iend,i,col[2];
39: PetscScalar value[] = { 1, 2 };
40: PetscBool flg,expmat;
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: 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);
65: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
66: Create a standalone EPS with appropriate settings
67: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
69: EPSCreate(PETSC_COMM_WORLD,&eps);
70: EPSGetST(eps,&st);
71: STSetType(st,STSINVERT);
72: STGetKSP(st,&ksp);
73: KSPSetType(ksp,KSPBCGS);
74: KSPGetPC(ksp,&pc);
75: PCSetType(pc,PCJACOBI);
76: EPSSetFromOptions(eps);
78: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
79: Compute singular values
80: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
82: SVDCreate(PETSC_COMM_WORLD,&svd);
83: SVDSetOperators(svd,A,NULL);
84: SVDSetType(svd,SVDCROSS);
85: SVDCrossSetEPS(svd,eps);
86: SVDSetWhichSingularTriplets(svd,SVD_SMALLEST);
87: SVDSetFromOptions(svd);
88: PetscObjectTypeCompare((PetscObject)svd,SVDCROSS,&flg);
89: if (flg) {
90: SVDCrossGetExplicitMatrix(svd,&expmat);
91: if (expmat) PetscPrintf(PETSC_COMM_WORLD," Using explicit matrix with cross solver\n");
92: }
93: SVDSolve(svd);
95: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
96: Display solution and clean up
97: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
98: SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
99: SVDDestroy(&svd);
100: EPSDestroy(&eps);
101: MatDestroy(&A);
102: SlepcFinalize();
103: return 0;
104: }
106: /*TEST
108: testset:
109: output_file: output/test6_1.out
110: test:
111: suffix: 1_subspace
112: args: -eps_type subspace
113: test:
114: suffix: 1_lobpcg
115: args: -eps_type lobpcg -st_type precond
116: test:
117: suffix: 2_cuda
118: args: -eps_type subspace -mat_type aijcusparse
119: requires: cuda
121: TEST*/