Actual source code: test4.c

slepc-3.18.2 2023-01-26
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  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[] = "Test the solution of a HEP without calling EPSSetFromOptions (based on ex1.c).\n\n"
 12:   "The command line options are:\n"
 13:   "  -n <n>, where <n> = number of grid subdivisions = matrix dimension.\n"
 14:   "  -type <eps_type> = eps type to test.\n\n";

 16: #include <slepceps.h>

 18: int main(int argc,char **argv)
 19: {
 20:   Mat            A;           /* problem matrix */
 21:   EPS            eps;         /* eigenproblem solver context */
 22:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
 23:   PetscInt       n=30,i,Istart,Iend,nev;
 24:   PetscBool      flg,gd2;
 25:   char           epstype[30] = "krylovschur";

 28:   SlepcInitialize(&argc,&argv,(char*)0,help);

 30:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 31:   PetscOptionsGetString(NULL,NULL,"-type",epstype,sizeof(epstype),NULL);
 32:   PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%" PetscInt_FMT "\n\n",n);

 34:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 35:      Compute the operator matrix that defines the eigensystem, Ax=kx
 36:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 38:   MatCreate(PETSC_COMM_WORLD,&A);
 39:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 40:   MatSetFromOptions(A);
 41:   MatSetUp(A);

 43:   MatGetOwnershipRange(A,&Istart,&Iend);
 44:   for (i=Istart;i<Iend;i++) {
 45:     if (i>0) MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);
 46:     if (i<n-1) MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);
 47:     MatSetValue(A,i,i,2.0,INSERT_VALUES);
 48:   }
 49:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 50:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 52:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 53:                 Create the eigensolver and set various options
 54:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 55:   /*
 56:      Create eigensolver context
 57:   */
 58:   EPSCreate(PETSC_COMM_WORLD,&eps);

 60:   /*
 61:      Set operators. In this case, it is a standard eigenvalue problem
 62:   */
 63:   EPSSetOperators(eps,A,NULL);
 64:   EPSSetProblemType(eps,EPS_HEP);
 65:   EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);
 66:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);

 68:   /*
 69:      Set solver parameters at runtime
 70:   */
 71:   PetscStrcmp(epstype,"gd2",&flg);
 72:   if (flg) {
 73:     EPSSetType(eps,EPSGD);
 74:     EPSGDSetDoubleExpansion(eps,PETSC_TRUE);
 75:     EPSGDGetDoubleExpansion(eps,&gd2);  /* not used */
 76:   } else EPSSetType(eps,epstype);
 77:   PetscStrcmp(epstype,"jd",&flg);
 78:   if (flg) {
 79:     EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
 80:     EPSSetTarget(eps,4.0);
 81:   }
 82:   PetscStrcmp(epstype,"lanczos",&flg);
 83:   if (flg) EPSLanczosSetReorthog(eps,EPS_LANCZOS_REORTHOG_LOCAL);
 84:   PetscObjectTypeCompareAny((PetscObject)eps,&flg,EPSRQCG,EPSLOBPCG,"");
 85:   if (flg) EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);

 87:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 88:                       Solve the eigensystem
 89:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 91:   EPSSolve(eps);
 92:   EPSGetDimensions(eps,&nev,NULL,NULL);
 93:   PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %" PetscInt_FMT "\n",nev);

 95:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 96:                     Display solution and clean up
 97:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

 99:   EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
100:   EPSDestroy(&eps);
101:   MatDestroy(&A);
102:   SlepcFinalize();
103:   return 0;
104: }

106: /*TEST

108:    testset:
109:       output_file: output/test4_1.out
110:       test:
111:          suffix: 1
112:          args: -type {{krylovschur subspace arnoldi lanczos gd jd gd2 lapack}}
113:       test:
114:          suffix: 1_arpack
115:          args: -type arpack
116:          requires: arpack
117:       test:
118:          suffix: 1_primme
119:          args: -type primme
120:          requires: primme
121:       test:
122:          suffix: 1_trlan
123:          args: -type trlan
124:          requires: trlan

126:    test:
127:       suffix: 2
128:       args: -type {{rqcg lobpcg}}

130: TEST*/