/*
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   SLEPc - Scalable Library for Eigenvalue Problem Computations
   Copyright (c) 2002-2021, Universitat Politecnica de Valencia, Spain

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

static char help[] = "Test pseudo-orthogonalization.\n\n";

#include <slepcds.h>

int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  PetscReal      *s,*ns;
  PetscScalar    *A;
  PetscInt       i,j,n=10;
  PetscViewer    viewer;
  PetscBool      verbose;

  ierr = SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
  ierr = PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);CHKERRQ(ierr);
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Test pseudo-orthogonalization for GHIEP - dimension %D.\n",n);CHKERRQ(ierr);
  ierr = PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSGHIEP);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);
  ierr = DSAllocate(ds,n);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,0,0,0);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
  }

  /* Fill with a symmetric Toeplitz matrix */
  ierr = DSGetArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  for (i=0;i<n;i++) A[i+i*n]=2.0;
  for (j=1;j<3;j++) {
    for (i=0;i<n-j;i++) { A[i+(i+j)*n]=1.0; A[(i+j)+i*n]=1.0; }
  }
  for (j=1;j<3;j++) { A[0+j*n]=-1.0*(j+2); A[j+0*n]=-1.0*(j+2); }
  ierr = DSRestoreArray(ds,DS_MAT_A,&A);CHKERRQ(ierr);
  ierr = DSSetState(ds,DS_STATE_RAW);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Signature matrix */
  ierr = PetscMalloc2(n,&s,n,&ns);CHKERRQ(ierr);
  s[0] = -1.0;
  for (i=1;i<n-1;i++) s[i]=1.0;
  s[n-1] = -1.0;

  /* Orthogonalize and show signature */
  ierr = DSPseudoOrthogonalize(ds,DS_MAT_A,n,s,NULL,ns);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"After pseudo-orthogonalize - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Resulting signature:\n");CHKERRQ(ierr);
  for (i=0;i<n;i++) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"%g\n",(double)ns[i]);CHKERRQ(ierr);
  }
  ierr = PetscFree2(s,ns);CHKERRQ(ierr);

  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return ierr;
}

/*TEST

   test:
      suffix: 1

TEST*/
