GCC Code Coverage Report

Directory: ./
File: src/eps/tutorials/ex3.c
Date: 2026-02-22 03:58:10
Exec Total Coverage
Lines: 69 73 94.5%
Functions: 4 4 100.0%
Branches: 145 260 55.8%
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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[] = "Solves the same eigenproblem as in example ex2, but using a shell matrix.\n\n"
12 "The problem is a standard symmetric eigenproblem corresponding to the 2-D Laplacian operator.\n\n"
13 "The command line options are:\n"
14 " -n <n>, where <n> = number of grid subdivisions in both x and y dimensions.\n\n";
15
16 #include <slepceps.h>
17
18 /*
19 User-defined routines
20 */
21 PetscErrorCode MatMult_Laplacian2D(Mat A,Vec x,Vec y);
22 PetscErrorCode MatGetDiagonal_Laplacian2D(Mat A,Vec diag);
23
24 16 int main(int argc,char **argv)
25 {
26 16 Mat A; /* operator matrix */
27 16 EPS eps; /* eigenproblem solver context */
28 16 EPSType type;
29 16 PetscMPIInt size;
30 16 PetscInt N,n=10,nev;
31 16 PetscBool terse;
32
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 16 PetscFunctionBeginUser;
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 16 PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
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 16 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size));
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 16 PetscCheck(size==1,PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"This is a uniprocessor example only");
37
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 16 PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
39 16 N = n*n;
40
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 16 PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\n2-D Laplacian Eigenproblem (matrix-free version), N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,n));
41
42 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
43 Create the operator matrix that defines the eigensystem, Ax=kx
44 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
45
46
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 16 PetscCall(MatCreateShell(PETSC_COMM_WORLD,N,N,N,N,&n,&A));
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 16 PetscCall(MatShellSetOperation(A,MATOP_MULT,(PetscErrorCodeFn*)MatMult_Laplacian2D));
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 16 PetscCall(MatShellSetOperation(A,MATOP_MULT_TRANSPOSE,(PetscErrorCodeFn*)MatMult_Laplacian2D));
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 16 PetscCall(MatShellSetOperation(A,MATOP_GET_DIAGONAL,(PetscErrorCodeFn*)MatGetDiagonal_Laplacian2D));
50
51 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
52 Create the eigensolver and set various options
53 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
54
55 /*
56 Create eigensolver context
57 */
58
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 16 PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
59
60 /*
61 Set operators. In this case, it is a standard eigenvalue problem
62 */
63
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 16 PetscCall(EPSSetOperators(eps,A,NULL));
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 16 PetscCall(EPSSetProblemType(eps,EPS_HEP));
65
66 /*
67 Set solver parameters at runtime
68 */
69
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 16 PetscCall(EPSSetFromOptions(eps));
70
71 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
72 Solve the eigensystem
73 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
74
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 16 PetscCall(EPSSolve(eps));
76
77 /*
78 Optional: Get some information from the solver and display it
79 */
80
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 16 PetscCall(EPSGetType(eps,&type));
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 16 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type));
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 16 PetscCall(EPSGetDimensions(eps,&nev,NULL,NULL));
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 16 PetscCall(PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev));
84
85 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
86 Display solution and clean up
87 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
88
89 /* show detailed info unless -terse option is given by user */
90
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 16 PetscCall(PetscOptionsHasName(NULL,NULL,"-terse",&terse));
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 16 if (terse) PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
92 else {
93 ✗ PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL));
94 ✗ PetscCall(EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD));
95 ✗ PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD));
96 ✗ PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
97 }
98
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 16 PetscCall(EPSDestroy(&eps));
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 16 PetscCall(MatDestroy(&A));
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 16 PetscCall(SlepcFinalize());
101 return 0;
102 }
103
104 /*
105 Compute the matrix vector multiplication y<---T*x where T is a nx by nx
106 tridiagonal matrix with DD on the diagonal, DL on the subdiagonal, and
107 DU on the superdiagonal.
108 */
109 239320 static void tv(int nx,const PetscScalar *x,PetscScalar *y)
110 {
111 239320 PetscScalar dd,dl,du;
112 239320 int j;
113
114 239320 dd = 4.0;
115 239320 dl = -1.0;
116 239320 du = -1.0;
117
118 239320 y[0] = dd*x[0] + du*x[1];
119
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 14295960 for (j=1;j<nx-1;j++)
120 14056640 y[j] = dl*x[j-1] + dd*x[j] + du*x[j+1];
121 239320 y[nx-1] = dl*x[nx-2] + dd*x[nx-1];
122 239320 }
123
124 /*
125 Matrix-vector product subroutine for the 2D Laplacian.
126
127 The matrix used is the 2 dimensional discrete Laplacian on unit square with
128 zero Dirichlet boundary condition.
129
130 Computes y <-- A*x, where A is the block tridiagonal matrix
131
132 | T -I |
133 |-I T -I |
134 A = | -I T |
135 | ... -I|
136 | -I T|
137
138 The subroutine TV is called to compute y<--T*x.
139 */
140 7068 PetscErrorCode MatMult_Laplacian2D(Mat A,Vec x,Vec y)
141 {
142 7068 void *ctx;
143 7068 int nx,lo,i,j;
144 7068 const PetscScalar *px;
145 7068 PetscScalar *py;
146
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 7068 PetscFunctionBeginUser;
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 7068 PetscCall(MatShellGetContext(A,&ctx));
149 7068 nx = *(int*)ctx;
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 7068 PetscCall(VecGetArrayRead(x,&px));
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 7068 PetscCall(VecGetArray(y,&py));
152
153 7068 tv(nx,&px[0],&py[0]);
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 253456 for (i=0;i<nx;i++) py[i] -= px[nx+i];
155
156
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 232252 for (j=2;j<nx;j++) {
157 225184 lo = (j-1)*nx;
158 225184 tv(nx,&px[lo],&py[lo]);
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 14507008 for (i=0;i<nx;i++) py[lo+i] -= px[lo-nx+i] + px[lo+nx+i];
160 }
161
162 7068 lo = (nx-1)*nx;
163 7068 tv(nx,&px[lo],&py[lo]);
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 253456 for (i=0;i<nx;i++) py[lo+i] -= px[lo-nx+i];
165
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 7068 PetscCall(VecRestoreArrayRead(x,&px));
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 7068 PetscCall(VecRestoreArray(y,&py));
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 1768 PetscFunctionReturn(PETSC_SUCCESS);
169 }
170
171 8 PetscErrorCode MatGetDiagonal_Laplacian2D(Mat A,Vec diag)
172 {
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 8 PetscFunctionBeginUser;
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 8 PetscCall(VecSet(diag,4.0));
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 2 PetscFunctionReturn(PETSC_SUCCESS);
176 }
177
178 /*TEST
179
180 test:
181 suffix: 1
182 args: -n 72 -eps_nev 4 -eps_ncv 20 -terse
183 requires: !single
184
185 test:
186 suffix: 2
187 args: -eps_nev 4 -st_type sinvert -st_ksp_type cg -st_pc_type jacobi -terse
188 requires: !single
189
190 TEST*/
191