Actual source code: test13.c

slepc-3.18.1 2022-11-02
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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 EPSSetArbitrarySelection.\n\n";

 13: #include <slepceps.h>

 15: PetscErrorCode MyArbitrarySelection(PetscScalar eigr,PetscScalar eigi,Vec xr,Vec xi,PetscScalar *rr,PetscScalar *ri,void *ctx)
 16: {
 17:   Vec             xref = *(Vec*)ctx;

 20:   VecDot(xr,xref,rr);
 21:   *rr = PetscAbsScalar(*rr);
 22:   if (ri) *ri = 0.0;
 23:   return 0;
 24: }

 26: int main(int argc,char **argv)
 27: {
 28:   Mat            A;           /* problem matrices */
 29:   EPS            eps;         /* eigenproblem solver context */
 30:   PetscScalar    seigr,seigi;
 31:   PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
 32:   Vec            sxr,sxi;
 33:   PetscInt       n=30,i,Istart,Iend,nconv;

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

 38:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 39:   PetscPrintf(PETSC_COMM_WORLD,"\nTridiagonal with zero diagonal, n=%" PetscInt_FMT "\n\n",n);

 41:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 42:            Create matrix tridiag([-1 0 -1])
 43:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 44:   MatCreate(PETSC_COMM_WORLD,&A);
 45:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);
 46:   MatSetFromOptions(A);
 47:   MatSetUp(A);

 49:   MatGetOwnershipRange(A,&Istart,&Iend);
 50:   for (i=Istart;i<Iend;i++) {
 51:     if (i>0) MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);
 52:     if (i<n-1) MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);
 53:   }
 54:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 55:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 57:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 58:                         Create the eigensolver
 59:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 60:   EPSCreate(PETSC_COMM_WORLD,&eps);
 61:   EPSSetProblemType(eps,EPS_HEP);
 62:   EPSSetTolerances(eps,tol,PETSC_DEFAULT);
 63:   EPSSetOperators(eps,A,NULL);
 64:   EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);
 65:   EPSSetFromOptions(eps);

 67:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 68:                 Solve eigenproblem and store some solution
 69:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 70:   EPSSolve(eps);
 71:   MatCreateVecs(A,&sxr,NULL);
 72:   MatCreateVecs(A,&sxi,NULL);
 73:   EPSGetConverged(eps,&nconv);
 74:   if (nconv>0) {
 75:     EPSGetEigenpair(eps,0,&seigr,&seigi,sxr,sxi);
 76:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);

 78:     /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 79:                  Solve eigenproblem using an arbitrary selection
 80:        - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 81:     EPSSetArbitrarySelection(eps,MyArbitrarySelection,&sxr);
 82:     EPSSetWhichEigenpairs(eps,EPS_LARGEST_MAGNITUDE);
 83:     EPSSolve(eps);
 84:     EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);
 85:   } else PetscPrintf(PETSC_COMM_WORLD,"Problem: no eigenpairs converged.\n");

 87:   EPSDestroy(&eps);
 88:   VecDestroy(&sxr);
 89:   VecDestroy(&sxi);
 90:   MatDestroy(&A);
 91:   SlepcFinalize();
 92:   return 0;
 93: }

 95: /*TEST

 97:    testset:
 98:       args: -eps_max_it 5000 -st_pc_type jacobi
 99:       output_file: output/test13_1.out
100:       filter: sed -e "s/-1.98975/-1.98974/"
101:       test:
102:          suffix: 1
103:          args: -eps_type {{krylovschur gd jd}}
104:       test:
105:          suffix: 1_gd2
106:          args: -eps_type gd -eps_gd_double_expansion
107:       test:
108:          suffix: 2
109:          args: -eps_non_hermitian -eps_type {{krylovschur gd jd}}
110:       test:
111:          suffix: 2_gd2
112:          args: -eps_non_hermitian -eps_type gd -eps_gd_double_expansion
113:          timeoutfactor: 2

115: TEST*/