Actual source code: test37.c
slepc-3.17.2 2022-08-09
1: /*
2: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3: SLEPc - Scalable Library for Eigenvalue Problem Computations
4: Copyright (c) 2002-, 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[] = "Tests solving an eigenproblem defined with MatNest. "
12: "Based on ex9.\n"
13: "The command line options are:\n"
14: " -n <n>, where <n> = block dimension of the 2x2 block matrix.\n"
15: " -L <L>, where <L> = bifurcation parameter.\n"
16: " -alpha <alpha>, -beta <beta>, -delta1 <delta1>, -delta2 <delta2>,\n"
17: " where <alpha> <beta> <delta1> <delta2> = model parameters.\n\n";
19: #include <slepceps.h>
21: /*
22: This example computes the eigenvalues with largest real part of the
23: following matrix
25: A = [ tau1*T+(beta-1)*I alpha^2*I
26: -beta*I tau2*T-alpha^2*I ],
28: where
30: T = tridiag{1,-2,1}
31: h = 1/(n+1)
32: tau1 = delta1/(h*L)^2
33: tau2 = delta2/(h*L)^2
34: */
36: int main(int argc,char **argv)
37: {
38: EPS eps;
39: Mat A,T1,T2,D1,D2,mats[4];
40: PetscScalar alpha,beta,tau1,tau2,delta1,delta2,L,h;
41: PetscInt N=30,i,Istart,Iend;
43: SlepcInitialize(&argc,&argv,(char*)0,help);
44: PetscOptionsGetInt(NULL,NULL,"-n",&N,NULL);
45: PetscPrintf(PETSC_COMM_WORLD,"\nBrusselator wave model, n=%" PetscInt_FMT "\n\n",N);
47: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
48: Generate the matrix
49: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
51: alpha = 2.0;
52: beta = 5.45;
53: delta1 = 0.008;
54: delta2 = 0.004;
55: L = 0.51302;
57: PetscOptionsGetScalar(NULL,NULL,"-L",&L,NULL);
58: PetscOptionsGetScalar(NULL,NULL,"-alpha",&alpha,NULL);
59: PetscOptionsGetScalar(NULL,NULL,"-beta",&beta,NULL);
60: PetscOptionsGetScalar(NULL,NULL,"-delta1",&delta1,NULL);
61: PetscOptionsGetScalar(NULL,NULL,"-delta2",&delta2,NULL);
63: h = 1.0 / (PetscReal)(N+1);
64: tau1 = delta1 / ((h*L)*(h*L));
65: tau2 = delta2 / ((h*L)*(h*L));
67: /* Create matrices T1, T2 */
68: MatCreate(PETSC_COMM_WORLD,&T1);
69: MatSetSizes(T1,PETSC_DECIDE,PETSC_DECIDE,N,N);
70: MatSetFromOptions(T1);
71: MatSetUp(T1);
72: MatGetOwnershipRange(T1,&Istart,&Iend);
73: for (i=Istart;i<Iend;i++) {
74: if (i>0) MatSetValue(T1,i,i-1,1.0,INSERT_VALUES);
75: if (i<N-1) MatSetValue(T1,i,i+1,1.0,INSERT_VALUES);
76: MatSetValue(T1,i,i,-2.0,INSERT_VALUES);
77: }
78: MatAssemblyBegin(T1,MAT_FINAL_ASSEMBLY);
79: MatAssemblyEnd(T1,MAT_FINAL_ASSEMBLY);
81: MatDuplicate(T1,MAT_COPY_VALUES,&T2);
82: MatScale(T1,tau1);
83: MatShift(T1,beta-1.0);
84: MatScale(T2,tau2);
85: MatShift(T2,-alpha*alpha);
87: /* Create matrices D1, D2 */
88: MatCreateConstantDiagonal(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,N,N,alpha*alpha,&D1);
89: MatCreateConstantDiagonal(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,N,N,-beta,&D2);
91: /* Create the nest matrix */
92: mats[0] = T1;
93: mats[1] = D1;
94: mats[2] = D2;
95: mats[3] = T2;
96: MatCreateNest(PETSC_COMM_WORLD,2,NULL,2,NULL,mats,&A);
98: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
99: Create the eigensolver and solve the problem
100: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
102: EPSCreate(PETSC_COMM_WORLD,&eps);
103: EPSSetOperators(eps,A,NULL);
104: EPSSetProblemType(eps,EPS_NHEP);
105: EPSSetWhichEigenpairs(eps,EPS_LARGEST_REAL);
106: EPSSetTrueResidual(eps,PETSC_FALSE);
107: EPSSetFromOptions(eps);
108: EPSSolve(eps);
110: /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
111: Display solution and clean up
112: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
114: EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
115: EPSDestroy(&eps);
116: MatDestroy(&A);
117: MatDestroy(&T1);
118: MatDestroy(&T2);
119: MatDestroy(&D1);
120: MatDestroy(&D2);
121: SlepcFinalize();
122: return 0;
123: }
125: /*TEST
127: test:
128: suffix: 1
129: args: -eps_nev 4
130: requires: !single
131: filter: sed -e "s/0.00019-2.13938i, 0.00019+2.13938i/0.00019+2.13938i, 0.00019-2.13938i/" | sed -e "s/-0.67192-2.52712i, -0.67192+2.52712i/-0.67192+2.52712i, -0.67192-2.52712i/"
133: TEST*/