/*
   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   SLEPc - Scalable Library for Eigenvalue Problem Computations
   Copyright (c) 2002-2020, Universitat Politecnica de Valencia, Spain

   This file is part of SLEPc.
   SLEPc is distributed under a 2-clause BSD license (see LICENSE).
   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/

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

#include <slepceps.h>

int main(int argc,char **argv)
{
  Mat            A;           /* problem matrix */
  EPS            eps;         /* eigenproblem solver context */
  PetscReal      tol=1000*PETSC_MACHINE_EPSILON;
  PetscInt       n=30,i,Istart,Iend,nev;
  PetscBool      flg,gd2;
  char           epstype[30] = "krylovschur";
  PetscErrorCode ierr;

  ierr = SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

  ierr = PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetString(NULL,NULL,"-type",epstype,sizeof(epstype),NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"\n1-D Laplacian Eigenproblem, n=%D\n\n",n);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     Compute the operator matrix that defines the eigensystem, Ax=kx
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
  ierr = MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,n,n);CHKERRQ(ierr);
  ierr = MatSetFromOptions(A);CHKERRQ(ierr);
  ierr = MatSetUp(A);CHKERRQ(ierr);

  ierr = MatGetOwnershipRange(A,&Istart,&Iend);CHKERRQ(ierr);
  for (i=Istart;i<Iend;i++) {
    if (i>0) { ierr = MatSetValue(A,i,i-1,-1.0,INSERT_VALUES);CHKERRQ(ierr); }
    if (i<n-1) { ierr = MatSetValue(A,i,i+1,-1.0,INSERT_VALUES);CHKERRQ(ierr); }
    ierr = MatSetValue(A,i,i,2.0,INSERT_VALUES);CHKERRQ(ierr);
  }
  ierr = MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
  ierr = MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                Create the eigensolver and set various options
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  /*
     Create eigensolver context
  */
  ierr = EPSCreate(PETSC_COMM_WORLD,&eps);CHKERRQ(ierr);

  /*
     Set operators. In this case, it is a standard eigenvalue problem
  */
  ierr = EPSSetOperators(eps,A,NULL);CHKERRQ(ierr);
  ierr = EPSSetProblemType(eps,EPS_HEP);CHKERRQ(ierr);
  ierr = EPSSetDimensions(eps,4,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
  ierr = EPSSetTolerances(eps,tol,PETSC_DEFAULT);CHKERRQ(ierr);

  /*
     Set solver parameters at runtime
  */
  ierr = PetscStrcmp(epstype,"gd2",&flg);CHKERRQ(ierr);
  if (flg) {
    ierr = EPSSetType(eps,EPSGD);CHKERRQ(ierr);
    ierr = EPSGDSetDoubleExpansion(eps,PETSC_TRUE);CHKERRQ(ierr);
    ierr = EPSGDGetDoubleExpansion(eps,&gd2);CHKERRQ(ierr);  /* not used */
  } else {
    ierr = EPSSetType(eps,epstype);CHKERRQ(ierr);
  }
  ierr = PetscStrcmp(epstype,"jd",&flg);CHKERRQ(ierr);
  if (flg) {
    ierr = EPSSetWhichEigenpairs(eps,EPS_TARGET_MAGNITUDE);CHKERRQ(ierr);
    ierr = EPSSetTarget(eps,4.0);CHKERRQ(ierr);
  }
  ierr = PetscObjectTypeCompareAny((PetscObject)eps,&flg,EPSRQCG,EPSLOBPCG,"");CHKERRQ(ierr);
  if (flg) {
    ierr = EPSSetWhichEigenpairs(eps,EPS_SMALLEST_REAL);CHKERRQ(ierr);
  }

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                      Solve the eigensystem
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = EPSSolve(eps);CHKERRQ(ierr);
  ierr = EPSGetDimensions(eps,&nev,NULL,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);CHKERRQ(ierr);

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                    Display solution and clean up
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);CHKERRQ(ierr);
  ierr = EPSDestroy(&eps);CHKERRQ(ierr);
  ierr = MatDestroy(&A);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return ierr;
}

/*TEST

   testset:
      output_file: output/test4_1.out
      test:
         suffix: 1
         args: -type {{krylovschur subspace arnoldi lanczos gd jd gd2 lapack}}
      test:
         suffix: 1_arpack
         args: -type arpack
         requires: arpack
      test:
         suffix: 1_primme
         args: -type primme
         requires: primme
      test:
         suffix: 1_trlan
         args: -type trlan
         requires: trlan

   testset:
      output_file: output/test4_2.out
      test:
         suffix: 2
         args: -type {{rqcg lobpcg}}
      test:
         suffix: 2_blzpack
         args: -type blzpack
         requires: blzpack

TEST*/
