Actual source code: test4.c

slepc-3.11.2 2019-07-30
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  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[] = "Solve a quadratic problem with PEPLINEAR with a user-provided EPS.\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 <slepcpep.h>

 18: int main(int argc,char **argv)
 19: {
 20:   Mat            M,C,K,A[3];
 21:   PEP            pep;
 22:   PetscInt       N,n=10,m,Istart,Iend,II,i,j;
 23:   PetscBool      flag,expmat;
 24:   PetscReal      alpha,beta;
 25:   EPS            eps;
 26:   ST             st;
 27:   KSP            ksp;
 28:   PC             pc;

 31:   SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 32:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 33:   PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag);
 34:   if (!flag) m=n;
 35:   N = n*m;
 36:   PetscPrintf(PETSC_COMM_WORLD,"\nQuadratic Eigenproblem, N=%D (%Dx%D grid)\n\n",N,n,m);

 38:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 39:      Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
 40:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 42:   /* K is the 2-D Laplacian */
 43:   MatCreate(PETSC_COMM_WORLD,&K);
 44:   MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,N,N);
 45:   MatSetFromOptions(K);
 46:   MatSetUp(K);
 47:   MatGetOwnershipRange(K,&Istart,&Iend);
 48:   for (II=Istart;II<Iend;II++) {
 49:     i = II/n; j = II-i*n;
 50:     if (i>0) { MatSetValue(K,II,II-n,-1.0,INSERT_VALUES); }
 51:     if (i<m-1) { MatSetValue(K,II,II+n,-1.0,INSERT_VALUES); }
 52:     if (j>0) { MatSetValue(K,II,II-1,-1.0,INSERT_VALUES); }
 53:     if (j<n-1) { MatSetValue(K,II,II+1,-1.0,INSERT_VALUES); }
 54:     MatSetValue(K,II,II,4.0,INSERT_VALUES);
 55:   }
 56:   MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY);
 57:   MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY);

 59:   /* C is the 1-D Laplacian on horizontal lines */
 60:   MatCreate(PETSC_COMM_WORLD,&C);
 61:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N);
 62:   MatSetFromOptions(C);
 63:   MatSetUp(C);
 64:   MatGetOwnershipRange(C,&Istart,&Iend);
 65:   for (II=Istart;II<Iend;II++) {
 66:     i = II/n; j = II-i*n;
 67:     if (j>0) { MatSetValue(C,II,II-1,-1.0,INSERT_VALUES); }
 68:     if (j<n-1) { MatSetValue(C,II,II+1,-1.0,INSERT_VALUES); }
 69:     MatSetValue(C,II,II,2.0,INSERT_VALUES);
 70:   }
 71:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 72:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 74:   /* M is a diagonal matrix */
 75:   MatCreate(PETSC_COMM_WORLD,&M);
 76:   MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,N,N);
 77:   MatSetFromOptions(M);
 78:   MatSetUp(M);
 79:   MatGetOwnershipRange(M,&Istart,&Iend);
 80:   for (II=Istart;II<Iend;II++) {
 81:     MatSetValue(M,II,II,(PetscReal)(II+1),INSERT_VALUES);
 82:   }
 83:   MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);
 84:   MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);

 86:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 87:              Create a standalone EPS with appropriate settings
 88:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 90:   EPSCreate(PETSC_COMM_WORLD,&eps);
 91:   EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
 92: #if defined(PETSC_USE_COMPLEX)
 93:   EPSSetTarget(eps,0.01*PETSC_i);
 94: #endif
 95:   EPSGetST(eps,&st);
 96:   STSetType(st,STSINVERT);
 97:   STGetKSP(st,&ksp);
 98:   KSPSetType(ksp,KSPBCGS);
 99:   KSPGetPC(ksp,&pc);
100:   PCSetType(pc,PCJACOBI);
101:   EPSSetFromOptions(eps);

103:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
104:              Create the eigensolver and solve the eigensystem
105:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

107:   PEPCreate(PETSC_COMM_WORLD,&pep);
108:   A[0] = K; A[1] = C; A[2] = M;
109:   PEPSetOperators(pep,3,A);
110:   PEPSetType(pep,PEPLINEAR);
111:   PEPSetProblemType(pep,PEP_GENERAL);
112:   PEPLinearSetEPS(pep,eps);
113:   PEPSetFromOptions(pep);
114:   PEPSolve(pep);
115:   PEPLinearGetLinearization(pep,&alpha,&beta);
116:   PetscPrintf(PETSC_COMM_WORLD," Linearization with alpha=%g, beta=%g",(double)alpha,(double)beta);
117:   PEPLinearGetExplicitMatrix(pep,&expmat);
118:   if (expmat) {
119:     PetscPrintf(PETSC_COMM_WORLD," with explicit matrix");
120:   }
121:   PetscPrintf(PETSC_COMM_WORLD,"\n");

123:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
124:                     Display solution and clean up
125:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

127:   PEPErrorView(pep,PEP_ERROR_BACKWARD,NULL);
128:   PEPDestroy(&pep);
129:   EPSDestroy(&eps);
130:   MatDestroy(&M);
131:   MatDestroy(&C);
132:   MatDestroy(&K);
133:   SlepcFinalize();
134:   return ierr;
135: }

137: /*TEST

139:    test:
140:       suffix: 1
141:       args: -pep_linear_explicitmatrix

143: TEST*/