Actual source code: test7.c
slepc-3.11.2 2019-07-30
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-2019, 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;
41: PetscErrorCode ierr;
43: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
45: PetscOptionsGetInt(NULL,NULL,"-m",&m,NULL);
46: PetscOptionsGetInt(NULL,NULL,"-n",&n,&flg);
47: if (!flg) n=m+2;
48: PetscPrintf(PETSC_COMM_WORLD,"\nRectangular bidiagonal matrix, m=%D n=%D\n\n",m,n);
50: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
51: Generate the matrix
52: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
54: MatCreate(PETSC_COMM_WORLD,&A);
55: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m,n);
56: MatSetFromOptions(A);
57: MatSetUp(A);
58: MatGetOwnershipRange(A,&Istart,&Iend);
59: for (i=Istart;i<Iend;i++) {
60: col[0]=i; col[1]=i+1;
61: if (i<n-1) {
62: MatSetValues(A,1,&i,2,col,value,INSERT_VALUES);
63: } else if (i==n-1) {
64: MatSetValue(A,i,col[0],value[0],INSERT_VALUES);
65: }
66: }
67: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
68: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
70: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
71: Create a standalone EPS with appropriate settings
72: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
74: EPSCreate(PETSC_COMM_WORLD,&eps);
75: EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
76: EPSSetTarget(eps,1.0);
77: EPSGetST(eps,&st);
78: STSetType(st,STSINVERT);
79: STSetShift(st,1.01);
80: STGetKSP(st,&ksp);
81: KSPSetType(ksp,KSPPREONLY);
82: KSPGetPC(ksp,&pc);
83: PCSetType(pc,PCLU);
84: EPSSetFromOptions(eps);
86: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
87: Compute singular values
88: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
90: SVDCreate(PETSC_COMM_WORLD,&svd);
91: SVDSetOperator(svd,A);
92: SVDSetType(svd,SVDCYCLIC);
93: SVDCyclicSetEPS(svd,eps);
94: SVDCyclicSetExplicitMatrix(svd,PETSC_TRUE);
95: SVDSetWhichSingularTriplets(svd,SVD_SMALLEST);
96: SVDSetFromOptions(svd);
97: PetscObjectTypeCompare((PetscObject)svd,SVDCYCLIC,&flg);
98: if (flg) {
99: SVDCyclicGetExplicitMatrix(svd,&expmat);
100: if (expmat) {
101: PetscPrintf(PETSC_COMM_WORLD," Using explicit matrix with cyclic solver\n",m,n);
102: }
103: }
104: SVDSolve(svd);
106: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
107: Display solution and clean up
108: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
109: SVDErrorView(svd,SVD_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
110: SVDDestroy(&svd);
111: EPSDestroy(&eps);
112: MatDestroy(&A);
113: SlepcFinalize();
114: return ierr;
115: }
117: /*TEST
119: test:
120: suffix: 1
121: args: -info_exclude svd -log_exclude svd
122: requires: !single
124: test:
125: suffix: 2_cuda
126: args: -info_exclude svd -log_exclude svd -mat_type aijcusparse
127: requires: cuda !single
128: output_file: output/test7_1.out
130: TEST*/