/*
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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 DSSVD with compact storage.\n\n";

#include <slepcds.h>

int main(int argc,char **argv)
{
  PetscErrorCode ierr;
  DS             ds;
  SlepcSC        sc;
  PetscReal      *T,sigma;
  PetscScalar    *w;
  PetscInt       i,n=10,m,l=2,k=5,ld;
  PetscViewer    viewer;
  PetscBool      verbose;

  ierr = SlepcInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
  ierr = PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);CHKERRQ(ierr);
  m = n;
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Solve a Dense System of type SVD with compact storage - dimension %Dx%D.\n",n,m);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(NULL,NULL,"-l",&l,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetInt(NULL,NULL,"-k",&k,NULL);CHKERRQ(ierr);
  if (l>n || k>n || l>k) SETERRQ(PETSC_COMM_WORLD,1,"Wrong value of dimensions");
  ierr = PetscOptionsHasName(NULL,NULL,"-verbose",&verbose);CHKERRQ(ierr);

  /* Create DS object */
  ierr = DSCreate(PETSC_COMM_WORLD,&ds);CHKERRQ(ierr);
  ierr = DSSetType(ds,DSSVD);CHKERRQ(ierr);
  ierr = DSSetFromOptions(ds);CHKERRQ(ierr);
  ld = n+2;  /* test leading dimension larger than n */
  ierr = DSAllocate(ds,ld);CHKERRQ(ierr);
  ierr = DSSetDimensions(ds,n,m,l,k);CHKERRQ(ierr);
  ierr = DSSetCompact(ds,PETSC_TRUE);CHKERRQ(ierr);

  /* Set up viewer */
  ierr = PetscViewerASCIIGetStdout(PETSC_COMM_WORLD,&viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO_DETAIL);CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);
  ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
  ierr = PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);

  /* Fill upper arrow-tridiagonal matrix */
  ierr = DSGetArrayReal(ds,DS_MAT_T,&T);CHKERRQ(ierr);
  for (i=0;i<n;i++) T[i] = (PetscReal)(i+1);
  for (i=l;i<n-1;i++) T[i+ld] = 1.0;
  ierr = DSRestoreArrayReal(ds,DS_MAT_T,&T);CHKERRQ(ierr);
  if (l==0 && k==0) {
    ierr = DSSetState(ds,DS_STATE_INTERMEDIATE);CHKERRQ(ierr);
  } else {
    ierr = DSSetState(ds,DS_STATE_RAW);CHKERRQ(ierr);
  }
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Initial - - - - - - - - -\n");CHKERRQ(ierr);
  ierr = DSView(ds,viewer);CHKERRQ(ierr);

  /* Solve */
  ierr = PetscMalloc1(n,&w);CHKERRQ(ierr);
  ierr = DSGetSlepcSC(ds,&sc);CHKERRQ(ierr);
  sc->comparison    = SlepcCompareLargestReal;
  sc->comparisonctx = NULL;
  sc->map           = NULL;
  sc->mapobj        = NULL;
  ierr = DSSolve(ds,w,NULL);CHKERRQ(ierr);
  ierr = DSSort(ds,w,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
  if (verbose) {
    ierr = PetscPrintf(PETSC_COMM_WORLD,"After solve - - - - - - - - -\n");CHKERRQ(ierr);
    ierr = DSView(ds,viewer);CHKERRQ(ierr);
  }

  /* Print singular values */
  ierr = PetscPrintf(PETSC_COMM_WORLD,"Computed singular values =\n");CHKERRQ(ierr);
  for (i=0;i<n;i++) {
    sigma = PetscRealPart(w[i]);
    ierr = PetscViewerASCIIPrintf(viewer,"  %.5f\n",(double)sigma);CHKERRQ(ierr);
  }
  ierr = PetscFree(w);CHKERRQ(ierr);
  ierr = DSDestroy(&ds);CHKERRQ(ierr);
  ierr = SlepcFinalize();
  return ierr;
}

/*TEST

   test:
      suffix: 1
      requires: !single

TEST*/
