Actual source code: ex2.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[] = "Standard symmetric eigenproblem corresponding to the Laplacian operator in 2 dimensions.\n\n"
12: "The command line options are:\n"
13: " -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
14: " -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";
16: #include <slepceps.h>
18: int main(int argc,char **argv)
19: {
20: Mat A; /* operator matrix */
21: EPS eps; /* eigenproblem solver context */
22: EPSType type;
23: PetscInt N,n=10,m,Istart,Iend,II,nev,i,j;
24: PetscBool flag,terse;
27: SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
29: PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
30: PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
31: if (!flag) m=n;
32: N = n*m;
33: PetscPrintf(PETSC_COMM_WORLD,"\n2-D Laplacian Eigenproblem, N=%D (%Dx%D grid)\n\n",N,n,m);
35: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
36: Compute the operator matrix that defines the eigensystem, Ax=kx
37: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
39: MatCreate(PETSC_COMM_WORLD,&A);
40: MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N);
41: MatSetFromOptions(A);
42: MatSetUp(A);
44: MatGetOwnershipRange(A,&Istart,&Iend);
45: for (II=Istart;II<Iend;II++) {
46: i = II/n; j = II-i*n;
47: if (i>0) { MatSetValue(A,II,II-n,-1.0,INSERT_VALUES); }
48: if (i<m-1) { MatSetValue(A,II,II+n,-1.0,INSERT_VALUES); }
49: if (j>0) { MatSetValue(A,II,II-1,-1.0,INSERT_VALUES); }
50: if (j<n-1) { MatSetValue(A,II,II+1,-1.0,INSERT_VALUES); }
51: MatSetValue(A,II,II,4.0,INSERT_VALUES);
52: }
54: MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
55: MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
57: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
58: Create the eigensolver and set various options
59: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
61: /*
62: Create eigensolver context
63: */
64: EPSCreate(PETSC_COMM_WORLD,&eps);
66: /*
67: Set operators. In this case, it is a standard eigenvalue problem
68: */
69: EPSSetOperators(eps,A,NULL);
70: EPSSetProblemType(eps,EPS_HEP);
72: /*
73: Set solver parameters at runtime
74: */
75: EPSSetFromOptions(eps);
77: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
78: Solve the eigensystem
79: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
81: EPSSolve(eps);
83: /*
84: Optional: Get some information from the solver and display it
85: */
86: EPSGetType(eps,&type);
87: PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);
88: EPSGetDimensions(eps,&nev,NULL,NULL);
89: PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);
91: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
92: Display solution and clean up
93: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
95: /* show detailed info unless -terse option is given by user */
96: PetscOptionsHasName(NULL,NULL,"-terse",&terse);
97: if (terse) {
98: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
99: } else {
100: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);
101: EPSReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);
102: EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);
103: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
104: }
105: EPSDestroy(&eps);
106: MatDestroy(&A);
107: SlepcFinalize();
108: return ierr;
109: }
111: /*TEST
113: testset:
114: args: -n 72 -eps_nev 4 -eps_ncv 20 -terse
115: requires: !single
116: output_file: output/ex2_1.out
117: test:
118: suffix: 1
119: test:
120: suffix: 2
121: args: -dynamic_library_preload
123: testset:
124: args: -n 30 -eps_type ciss -terse
125: requires: double
126: output_file: output/ex2_ciss.out
127: test:
128: suffix: ciss_1
129: nsize: 1
130: args: -rg_type interval -rg_interval_endpoints 1.1,1.25
131: test:
132: suffix: ciss_2
133: nsize: 2
134: args: -rg_type ellipse -rg_ellipse_center 1.175 -rg_ellipse_radius 0.075 -eps_ciss_partitions 2
136: TEST*/