/*
   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
   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[] = "Solves a generalized eigensystem Ax=kBx with matrices loaded from a file.\n"
  "The command line options are:\n"
  "  -f1 <filename> -f2 <filename>, PETSc binary files containing A and B.\n"
  "  -evecs <filename>, output file to save computed eigenvectors.\n"
  "  -ninitial <nini>, number of user-provided initial guesses.\n"
  "  -finitial <filename>, binary file containing <nini> vectors.\n"
  "  -nconstr <ncon>, number of user-provided constraints.\n"
  "  -fconstr <filename>, binary file containing <ncon> vectors.\n\n";

#include <slepceps.h>

int main(int argc,char **argv)
{
  Mat            A,B;             /* matrices */
  EPS            eps;             /* eigenproblem solver context */
  ST             st;
  KSP            ksp;
  EPSType        type;
  PetscReal      tol;
  Vec            xr,xi,*Iv,*Cv;
  PetscInt       nev,maxit,i,its,lits,nconv,nini=0,ncon=0;
  char           filename[PETSC_MAX_PATH_LEN];
  PetscViewer    viewer;
  PetscBool      flg,evecs,ishermitian,terse;
  PetscErrorCode ierr;

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

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        Load the matrices that define the eigensystem, Ax=kBx
     - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

  ierr = PetscPrintf(PETSC_COMM_WORLD,"\nGeneralized eigenproblem stored in file.\n\n");CHKERRQ(ierr);
  ierr = PetscOptionsGetString(NULL,NULL,"-f1",filename,sizeof(filename),&flg);CHKERRQ(ierr);
  if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must indicate a file name for matrix A with the -f1 option");

#if defined(PETSC_USE_COMPLEX)
  ierr = PetscPrintf(PETSC_COMM_WORLD," Reading COMPLEX matrices from binary files...\n");CHKERRQ(ierr);
#else
  ierr = PetscPrintf(PETSC_COMM_WORLD," Reading REAL matrices from binary files...\n");CHKERRQ(ierr);
#endif
  ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);CHKERRQ(ierr);
  ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
  ierr = MatSetFromOptions(A);CHKERRQ(ierr);
  ierr = MatLoad(A,viewer);CHKERRQ(ierr);
  ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);

  ierr = PetscOptionsGetString(NULL,NULL,"-f2",filename,sizeof(filename),&flg);CHKERRQ(ierr);
  if (flg) {
    ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);CHKERRQ(ierr);
    ierr = MatCreate(PETSC_COMM_WORLD,&B);CHKERRQ(ierr);
    ierr = MatSetFromOptions(B);CHKERRQ(ierr);
    ierr = MatLoad(B,viewer);CHKERRQ(ierr);
    ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
  } else {
    ierr = PetscPrintf(PETSC_COMM_WORLD," Matrix B was not provided, setting B=I\n\n");CHKERRQ(ierr);
    B = NULL;
  }

  ierr = MatCreateVecs(A,NULL,&xr);CHKERRQ(ierr);
  ierr = MatCreateVecs(A,NULL,&xi);CHKERRQ(ierr);

  /*
     Read user constraints if available
  */
  ierr = PetscOptionsGetInt(NULL,NULL,"-nconstr",&ncon,&flg);CHKERRQ(ierr);
  if (flg) {
    if (ncon<=0) SETERRQ(PETSC_COMM_WORLD,1,"The number of constraints must be >0");
    ierr = PetscOptionsGetString(NULL,NULL,"-fconstr",filename,sizeof(filename),&flg);CHKERRQ(ierr);
    if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must specify the name of the file storing the constraints");
    ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);CHKERRQ(ierr);
    ierr = VecDuplicateVecs(xr,ncon,&Cv);CHKERRQ(ierr);
    for (i=0;i<ncon;i++) {
      ierr = VecLoad(Cv[i],viewer);CHKERRQ(ierr);
    }
    ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
  }

  /*
     Read initial guesses if available
  */
  ierr = PetscOptionsGetInt(NULL,NULL,"-ninitial",&nini,&flg);CHKERRQ(ierr);
  if (flg) {
    if (nini<=0) SETERRQ(PETSC_COMM_WORLD,1,"The number of initial vectors must be >0");
    ierr = PetscOptionsGetString(NULL,NULL,"-finitial",filename,sizeof(filename),&flg);CHKERRQ(ierr);
    if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must specify the name of the file containing the initial vectors");
    ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);CHKERRQ(ierr);
    ierr = VecDuplicateVecs(xr,nini,&Iv);CHKERRQ(ierr);
    for (i=0;i<nini;i++) {
      ierr = VecLoad(Iv[i],viewer);CHKERRQ(ierr);
    }
    ierr = PetscViewerDestroy(&viewer);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 generalized eigenvalue problem
  */
  ierr = EPSSetOperators(eps,A,B);CHKERRQ(ierr);

  /*
     If the user provided initial guesses or constraints, pass them here
  */
  ierr = EPSSetInitialSpace(eps,nini,Iv);CHKERRQ(ierr);
  ierr = EPSSetDeflationSpace(eps,ncon,Cv);CHKERRQ(ierr);

  /*
     Set solver parameters at runtime
  */
  ierr = EPSSetFromOptions(eps);CHKERRQ(ierr);

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

  ierr = EPSSolve(eps);CHKERRQ(ierr);

  /*
     Optional: Get some information from the solver and display it
  */
  ierr = EPSGetIterationNumber(eps,&its);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of iterations of the method: %D\n",its);CHKERRQ(ierr);
  ierr = EPSGetST(eps,&st);CHKERRQ(ierr);
  ierr = STGetKSP(st,&ksp);CHKERRQ(ierr);
  ierr = KSPGetTotalIterations(ksp,&lits);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of linear iterations of the method: %D\n",lits);CHKERRQ(ierr);
  ierr = EPSGetType(eps,&type);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Solution method: %s\n\n",type);CHKERRQ(ierr);
  ierr = EPSGetDimensions(eps,&nev,NULL,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Number of requested eigenvalues: %D\n",nev);CHKERRQ(ierr);
  ierr = EPSGetTolerances(eps,&tol,&maxit);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD," Stopping condition: tol=%.4g, maxit=%D\n",(double)tol,maxit);CHKERRQ(ierr);

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

  /*
     Show detailed info unless -terse option is given by user
   */
  ierr = PetscOptionsHasName(NULL,NULL,"-terse",&terse);CHKERRQ(ierr);
  if (terse) {
    ierr = EPSErrorView(eps,EPS_ERROR_RELATIVE,NULL);CHKERRQ(ierr);
  } else {
    ierr = PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
    ierr = EPSConvergedReasonView(eps,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
    ierr = EPSErrorView(eps,EPS_ERROR_RELATIVE,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
    ierr = PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
  }

  /*
     Save eigenvectors, if requested
  */
  ierr = PetscOptionsGetString(NULL,NULL,"-evecs",filename,sizeof(filename),&evecs);CHKERRQ(ierr);
  ierr = EPSGetConverged(eps,&nconv);CHKERRQ(ierr);
  if (nconv>0 && evecs) {
    ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_WRITE,&viewer);CHKERRQ(ierr);
    ierr = EPSIsHermitian(eps,&ishermitian);CHKERRQ(ierr);
    for (i=0;i<nconv;i++) {
      ierr = EPSGetEigenvector(eps,i,xr,xi);CHKERRQ(ierr);
      ierr = VecView(xr,viewer);CHKERRQ(ierr);
#if !defined(PETSC_USE_COMPLEX)
      if (!ishermitian) { ierr = VecView(xi,viewer);CHKERRQ(ierr); }
#endif
    }
    ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
  }

  /*
     Free work space
  */
  ierr = EPSDestroy(&eps);CHKERRQ(ierr);
  ierr = MatDestroy(&A);CHKERRQ(ierr);
  ierr = MatDestroy(&B);CHKERRQ(ierr);
  ierr = VecDestroy(&xr);CHKERRQ(ierr);
  ierr = VecDestroy(&xi);CHKERRQ(ierr);
  if (nini > 0) {
    ierr = VecDestroyVecs(nini,&Iv);CHKERRQ(ierr);
  }
  if (ncon > 0) {
    ierr = VecDestroyVecs(ncon,&Cv);CHKERRQ(ierr);
  }
  ierr = SlepcFinalize();
  return ierr;
}

/*TEST

   test:
      suffix: 1
      args: -f1 ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62a.petsc -f2 ${SLEPC_DIR}/share/slepc/datafiles/matrices/bfw62b.petsc -eps_nev 4 -terse
      requires: double !complex !define(PETSC_USE_64BIT_INDICES)

   test:
      suffix: ciss_1
      args: -f1 ${DATAFILESPATH}/matrices/complex/mhd1280a.petsc -f2 ${DATAFILESPATH}/matrices/complex/mhd1280b.petsc -eps_type ciss -eps_ciss_usest 0 -eps_ciss_quadrule chebyshev -rg_type ring -rg_ring_center 0 -rg_ring_radius .49 -rg_ring_width 0.2 -rg_ring_startangle .25 -rg_ring_endangle .49 -terse
      requires: complex datafilespath !define(PETSC_USE_64BIT_INDICES)
      timeoutfactor: 2

TEST*/
