Actual source code: test7.c
slepc-3.23.0 2025-03-29
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 cyclic 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: PetscFunctionBeginUser;
43: PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
45: PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL));
46: PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg));
47: if (!flg) n=m+2;
48: PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%" PetscInt_FMT " n=%" PetscInt_FMT "\n\n",m,n));
50: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
51: Generate the matrix
52: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
54: PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
55: PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n));
56: PetscCall(MatSetFromOptions(A));
57: PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
58: for (i=Istart;i<Iend;i++) {
59: col[0]=i; col[1]=i+1;
60: if (i<n-1) PetscCall(MatSetValues(A,1,&i,2,col,value,INSERT_VALUES));
61: else if (i==n-1) PetscCall(MatSetValue(A,i,col[0],value[0],INSERT_VALUES));
62: }
63: PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
64: PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
66: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
67: Create a standalone EPS with appropriate settings
68: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
70: PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
71: PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE));
72: PetscCall(EPSSetTarget(eps,1.0));
73: PetscCall(EPSGetST(eps,&st));
74: PetscCall(STSetType(st,STSINVERT));
75: PetscCall(STSetShift(st,1.01));
76: PetscCall(STGetKSP(st,&ksp));
77: PetscCall(KSPSetType(ksp,KSPPREONLY));
78: PetscCall(KSPGetPC(ksp,&pc));
79: PetscCall(PCSetType(pc,PCLU));
80: PetscCall(EPSSetFromOptions(eps));
82: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
83: Compute singular values
84: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
86: PetscCall(SVDCreate(PETSC_COMM_WORLD,&svd));
87: PetscCall(SVDSetOperators(svd,A,NULL));
88: PetscCall(SVDSetType(svd,SVDCYCLIC));
89: PetscCall(SVDCyclicSetEPS(svd,eps));
90: PetscCall(SVDCyclicSetExplicitMatrix(svd,PETSC_TRUE));
91: PetscCall(SVDSetWhichSingularTriplets(svd,SVD_SMALLEST));
92: PetscCall(SVDSetFromOptions(svd));
93: PetscCall(PetscObjectTypeCompare((PetscObject)svd,SVDCYCLIC,&flg));
94: if (flg) {
95: PetscCall(SVDCyclicGetExplicitMatrix(svd,&expmat));
96: if (expmat) PetscCall(PetscPrintf(PETSC_COMM_WORLD," Using explicit matrix with cyclic solver\n"));
97: }
98: PetscCall(SVDSolve(svd));
100: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
101: Display solution and clean up
102: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
103: PetscCall(SVDErrorView(svd,SVD_ERROR_ABSOLUTE,PETSC_VIEWER_STDOUT_WORLD));
104: PetscCall(SVDDestroy(&svd));
105: PetscCall(EPSDestroy(&eps));
106: PetscCall(MatDestroy(&A));
107: PetscCall(SlepcFinalize());
108: return 0;
109: }
111: /*TEST
113: test:
114: suffix: 1
115: args: -log_exclude svd
117: testset:
118: args: -log_exclude svd
119: output_file: output/test7_1.out
120: test:
121: suffix: 2_cuda
122: args: -mat_type aijcusparse
123: requires: cuda
124: test:
125: suffix: 2_hip
126: args: -mat_type aijhipsparse
127: requires: hip
129: TEST*/