Actual source code: test4.c

slepc-3.17.2 2022-08-09
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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";

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

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

 33:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 34:      Compute the operator matrix that defines the eigensystem, Ax=kx
 35:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

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

 51:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 52:                 Create the eigensolver and set various options
 53:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 54:   /*
 55:      Create eigensolver context
 56:   */
 57:   EPSCreate(PETSC_COMM_WORLD,&eps);

 59:   /*
 60:      Set operators. In this case, it is a standard eigenvalue problem
 61:   */
 62:   EPSSetOperators(eps,A,NULL);
 63:   EPSSetProblemType(eps,EPS_HEP);
 64:   EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);
 65:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);

 67:   /*
 68:      Set solver parameters at runtime
 69:   */
 70:   PetscStrcmp(epstype,"gd2",&flg);
 71:   if (flg) {
 72:     EPSSetType(eps,EPSGD);
 73:     EPSGDSetDoubleExpansion(eps,PETSC_TRUE);
 74:     EPSGDGetDoubleExpansion(eps,&gd2);  /* not used */
 75:   } else EPSSetType(eps,epstype);
 76:   PetscStrcmp(epstype,"jd",&flg);
 77:   if (flg) {
 78:     EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);
 79:     EPSSetTarget(eps,4.0);
 80:   }
 81:   PetscStrcmp(epstype,"lanczos",&flg);
 82:   if (flg) EPSLanczosSetReorthog(eps,EPS_LANCZOS_REORTHOG_LOCAL);
 83:   PetscObjectTypeCompareAny((PetscObject)eps,&flg,EPSRQCG,EPSLOBPCG,"");
 84:   if (flg) EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);

 86:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 87:                       Solve the eigensystem
 88:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

 94:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 95:                     Display solution and clean up
 96:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

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

105: /*TEST

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

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

129: TEST*/