GCC Code Coverage Report

Directory: ./
File: src/svd/tutorials/ex15.c
Date: 2025-10-04 04:19:13
Exec Total Coverage
Lines: 52 52 100.0%
Functions: 1 1 100.0%
Branches: 170 252 67.5%
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1 /*
2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3 SLEPc - Scalable Library for Eigenvalue Problem Computations
4 Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
5
6 This file is part of SLEPc.
7 SLEPc is distributed under a 2-clause BSD license (see LICENSE).
8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
9 */
10
11 static char help[] = "Singular value decomposition of the Lauchli matrix.\n\n"
12 "The command line options are:\n"
13 " -n <n>, where <n> = matrix dimension.\n"
14 " -mu <mu>, where <mu> = subdiagonal value.\n\n";
15
16 #include <slepcsvd.h>
17
18 22 int main(int argc,char **argv)
19 {
20 22 Mat A; /* operator matrix */
21 22 Vec u,v; /* left and right singular vectors */
22 22 SVD svd; /* singular value problem solver context */
23 22 SVDType type;
24 22 PetscReal error,tol,sigma,mu=PETSC_SQRT_MACHINE_EPSILON;
25 22 PetscInt n=100,i,j,Istart,Iend,nsv,maxit,its,nconv;
26
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 22 PetscFunctionBeginUser;
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 22 PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
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 22 PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
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 22 PetscCall(PetscOptionsGetReal(NULL,NULL,"-mu",&mu,NULL));
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nLauchli singular value decomposition, (%" PetscInt_FMT " x %" PetscInt_FMT ") mu=%g\n\n",n+1,n,(double)mu));
33
34 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
35 Build the Lauchli matrix
36 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
37
38
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 22 PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
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 22 PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n+1,n));
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 22 PetscCall(MatSetFromOptions(A));
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 22 PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
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 1840 for (i=Istart;i<Iend;i++) {
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 1818 if (i == 0) {
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 1818 for (j=0;j<n;j++) PetscCall(MatSetValue(A,0,j,1.0,INSERT_VALUES));
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 1818 } else PetscCall(MatSetValue(A,i,i-1,mu,INSERT_VALUES));
47 }
48
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 22 PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
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 22 PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
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 22 PetscCall(MatCreateVecs(A,&v,&u));
52
53 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
54 Create the singular value solver and set various options
55 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
56
57 /*
58 Create singular value solver context
59 */
60
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 22 PetscCall(SVDCreate(PETSC_COMM_WORLD,&svd));
61
62 /*
63 Set operators and problem type
64 */
65
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 22 PetscCall(SVDSetOperators(svd,A,NULL));
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 22 PetscCall(SVDSetProblemType(svd,SVD_STANDARD));
67
68 /*
69 Use thick-restart Lanczos as default solver
70 */
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 22 PetscCall(SVDSetType(svd,SVDTRLANCZOS));
72
73 /*
74 Set solver parameters at runtime
75 */
76
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 22 PetscCall(SVDSetFromOptions(svd));
77
78 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
79 Solve the singular value system
80 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
81
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 22 PetscCall(SVDSolve(svd));
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 22 PetscCall(SVDGetIterationNumber(svd,&its));
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %" PetscInt_FMT "\n",its));
85
86 /*
87 Optional: Get some information from the solver and display it
88 */
89
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 22 PetscCall(SVDGetType(svd,&type));
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type));
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 22 PetscCall(SVDGetDimensions(svd,&nsv,NULL,NULL));
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of requested singular values: %" PetscInt_FMT "\n",nsv));
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 22 PetscCall(SVDGetTolerances(svd,&tol,&maxit));
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%" PetscInt_FMT "\n",(double)tol,maxit));
95
96 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
97 Display solution and clean up
98 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
99
100 /*
101 Get number of converged singular triplets
102 */
103
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 22 PetscCall(SVDGetConverged(svd,&nconv));
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of converged approximate singular triplets: %" PetscInt_FMT "\n\n",nconv));
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 22 if (nconv>0) {
107 /*
108 Display singular values and relative errors
109 */
110
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD,
111 " sigma relative error\n"
112 " --------------------- ------------------\n"));
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 1322 for (i=0;i<nconv;i++) {
114 /*
115 Get converged singular triplets: i-th singular value is stored in sigma
116 */
117
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 1300 PetscCall(SVDGetSingularTriplet(svd,i,&sigma,u,v));
118
119 /*
120 Compute the error associated to each singular triplet
121 */
122
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 1300 PetscCall(SVDComputeError(svd,i,SVD_ERROR_RELATIVE,&error));
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 1300 PetscCall(PetscPrintf(PETSC_COMM_WORLD," % 6f ",(double)sigma));
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 1300 PetscCall(PetscPrintf(PETSC_COMM_WORLD," % 12g\n",(double)error));
126 }
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 22 PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n"));
128 }
129
130 /*
131 Free work space
132 */
133
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 22 PetscCall(SVDDestroy(&svd));
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 22 PetscCall(MatDestroy(&A));
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 22 PetscCall(VecDestroy(&u));
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 22 PetscCall(VecDestroy(&v));
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 22 PetscCall(SlepcFinalize());
138 return 0;
139 }
140
141 /*TEST
142
143 testset:
144 filter: sed -e "s/[0-9]\.[0-9]*e[+-]\([0-9]*\)/removed/g"
145 requires: double
146 test:
147 suffix: 1
148 test:
149 suffix: 1_scalapack
150 nsize: {{1 2}}
151 args: -svd_type scalapack
152 requires: scalapack
153
154 TEST*/
155