GCC Code Coverage Report

Directory: ./
File: src/eps/tutorials/ex11.c
Date: 2025-12-10 04:20:18
Exec Total Coverage
Lines: 48 52 92.3%
Functions: 1 1 100.0%
Branches: 148 244 60.7%
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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[] = "Computes the smallest nonzero eigenvalue of the Laplacian of a graph.\n\n"
12 "This example illustrates EPSSetDeflationSpace(). The example graph corresponds to a "
13 "2-D regular mesh. The command line options are:\n"
14 " -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
15 " -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";
16
17 #include <slepceps.h>
18
19 20 int main (int argc,char **argv)
20 {
21 20 EPS eps; /* eigenproblem solver context */
22 20 Mat A; /* operator matrix */
23 20 Vec x;
24 20 EPSType type;
25 20 PetscInt N,n=10,m,i,j,II,Istart,Iend,nev;
26 20 PetscScalar w;
27 20 PetscBool flag,terse;
28
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 20 PetscFunctionBeginUser;
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 20 PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
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 20 PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
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 20 PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag));
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 20 if (!flag) m=n;
35 20 N = n*m;
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 20 PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nFiedler vector of a 2-D regular mesh, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m));
37
38 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
39 Compute the operator matrix that defines the eigensystem, Ax=kx
40 In this example, A = L(G), where L is the Laplacian of graph G, i.e.
41 Lii = degree of node i, Lij = -1 if edge (i,j) exists in G
42 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
43
44
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 20 PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
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 20 PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N));
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 20 PetscCall(MatSetFromOptions(A));
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 20 PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
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 2020 for (II=Istart;II<Iend;II++) {
50 2000 i = II/n; j = II-i*n;
51 2000 w = 0.0;
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 2000 if (i>0) { PetscCall(MatSetValue(A,II,II-n,-1.0,INSERT_VALUES)); w=w+1.0; }
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 2000 if (i<m-1) { PetscCall(MatSetValue(A,II,II+n,-1.0,INSERT_VALUES)); w=w+1.0; }
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 2000 if (j>0) { PetscCall(MatSetValue(A,II,II-1,-1.0,INSERT_VALUES)); w=w+1.0; }
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 2000 if (j<n-1) { PetscCall(MatSetValue(A,II,II+1,-1.0,INSERT_VALUES)); w=w+1.0; }
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 2000 PetscCall(MatSetValue(A,II,II,w,INSERT_VALUES));
57 }
58
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 20 PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
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 20 PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
61
62 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
63 Create the eigensolver and set various options
64 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
65
66 /*
67 Create eigensolver context
68 */
69
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 20 PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
70
71 /*
72 Set operators. In this case, it is a standard eigenvalue problem
73 */
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 20 PetscCall(EPSSetOperators(eps,A,NULL));
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 20 PetscCall(EPSSetProblemType(eps,EPS_HEP));
76
77 /*
78 Select portion of spectrum
79 */
80
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 20 PetscCall(EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL));
81
82 /*
83 Set solver parameters at runtime
84 */
85
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 20 PetscCall(EPSSetFromOptions(eps));
86
87 /*
88 Attach deflation space: in this case, the matrix has a constant
89 nullspace, [1 1 ... 1]^T is the eigenvector of the zero eigenvalue
90 */
91
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 20 PetscCall(MatCreateVecs(A,&x,NULL));
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 20 PetscCall(VecSet(x,1.0));
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 20 PetscCall(EPSSetDeflationSpace(eps,1,&x));
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 20 PetscCall(VecDestroy(&x));
95
96 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
97 Solve the eigensystem
98 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
99
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 20 PetscCall(EPSSolve(eps));
101
102 /*
103 Optional: Get some information from the solver and display it
104 */
105
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 20 PetscCall(EPSGetType(eps,&type));
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 20 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type));
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 20 PetscCall(EPSGetDimensions(eps,&nev,NULL,NULL));
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 20 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev));
109
110 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
111 Display solution and clean up
112 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
113
114 /* show detailed info unless -terse option is given by user */
115
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 20 PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
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 20 if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
117 else {
118 ✗ PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
119 ✗ PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
120 ✗ PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
121 ✗ PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
122 }
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 20 PetscCall(EPSDestroy(&eps));
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 20 PetscCall(MatDestroy(&A));
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 20 PetscCall(SlepcFinalize());
126 return 0;
127 }
128
129 /*TEST
130
131 testset:
132 args: -eps_nev 4 -terse
133 output_file: output/ex11_1.out
134 test:
135 suffix: 1
136 args: -eps_krylovschur_restart .2
137 test:
138 suffix: 2
139 args: -eps_ncv 20 -eps_target 0 -st_type sinvert -st_ksp_type cg -st_pc_type jacobi
140
141 TEST*/
142