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 changing EPS type.\n\n";

 13: #include <slepceps.h>

 15: int main(int argc,char **argv)
 16: {
 17:   Mat            A;           /* problem matrix */
 18:   EPS            eps;         /* eigenproblem solver context */
 19:   ST             st;
 20:   KSP            ksp;
 21:   PetscInt       n=20,i,Istart,Iend,nrest;

 23:   PetscFunctionBeginUser;
 24:   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
 25:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nDiagonal Eigenproblem, n=%" PetscInt_FMT "\n\n",n));

 27:   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
 28:   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n));
 29:   PetscCall(MatSetFromOptions(A));
 30:   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
 31:   for (i=Istart;i<Iend;i++) PetscCall(MatSetValue(A,i,i,i+1,INSERT_VALUES));
 32:   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
 33:   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));

 35:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 36:              Create eigensolver and view options
 37:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 38:   PetscCall(EPSCreate(PETSC_COMM_WORLD,&eps));
 39:   PetscCall(EPSSetOperators(eps,A,NULL));
 40:   PetscCall(EPSSetProblemType(eps,EPS_HEP));
 41:   PetscCall(EPSSetTarget(eps,4.8));
 42:   PetscCall(EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE));
 43:   PetscCall(EPSSetDimensions(eps,4,PETSC_DETERMINE,PETSC_DETERMINE));

 45:   PetscCall(EPSSetType(eps,EPSRQCG));
 46:   PetscCall(EPSRQCGSetReset(eps,10));
 47:   PetscCall(EPSSetFromOptions(eps));
 48:   PetscCall(EPSRQCGGetReset(eps,&nrest));
 49:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"RQCG reset parameter = %" PetscInt_FMT "\n\n",nrest));
 50:   PetscCall(EPSView(eps,NULL));

 52:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 53:              Change eigensolver type and solve problem
 54:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 55:   PetscCall(EPSSetType(eps,EPSGD));
 56:   PetscCall(EPSGetST(eps,&st));
 57:   PetscCall(STGetKSP(st,&ksp));
 58:   PetscCall(KSPSetType(ksp,KSPPREONLY));
 59:   PetscCall(EPSSolve(eps));
 60:   PetscCall(EPSView(eps,NULL));

 62:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 63:                     Display solution and clean up
 64:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 65:   PetscCall(EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL));
 66:   PetscCall(EPSDestroy(&eps));
 67:   PetscCall(MatDestroy(&A));
 68:   PetscCall(SlepcFinalize());
 69:   return 0;
 70: }

 72: /*TEST

 74:    test:
 75:       suffix: 1
 76:       args: -eps_harmonic -eps_conv_norm
 77:       filter: grep -v tolerance | sed -e "s/symmetric/hermitian/"

 79: TEST*/