#ifdef PETSC_RCS_HEADER
static char vcid[] = "$Id: shellcnv.c,v 1.4 1997/07/09 20:54:17 balay Exp bsmith $";
#endif


#include "petsc.h"
#include "src/mat/matimpl.h"        /*I "mat.h" I*/
#include "src/vec/vecimpl.h"  
  
#undef __FUNC__  
#define __FUNC__ "MatConvert_Shell"
int MatConvert_Shell(Mat oldmat,MatType newtype, Mat *mat)
{
  Vec      in,out;
  int      ierr,i,M,m,size,*rows,start,end;
  MPI_Comm comm;
  Scalar   *array,zero = 0.0,one = 1.0;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(oldmat,MAT_COOKIE);
  PetscValidPointer(mat);

  if (newtype != MATSEQDENSE || newtype != MATMPIDENSE) {
    SETERRQ(PETSC_ERR_SUP,1,"Can only convert shell matrices to dense currently");
  }
  comm = oldmat->comm;

  MPI_Comm_size(comm,&size);

  ierr = MatGetOwnershipRange(oldmat,&start,&end); CHKERRQ(ierr);
  ierr = VecCreateMPI(comm,end-start,PETSC_DECIDE,&in); CHKERRQ(ierr);
  ierr = VecDuplicate(in,&out); CHKERRQ(ierr);
  ierr = VecGetSize(in,&M); CHKERRQ(ierr);
  ierr = VecGetLocalSize(in,&m); CHKERRQ(ierr);
  rows = (int *) PetscMalloc( (m+1)*sizeof(int) ); CHKPTRQ(rows);
  for ( i=0; i<m; i++ ) {rows[i] = start + i;}

  if (size == 1) {
    ierr = MatCreateSeqDense(comm,M,M,PETSC_NULL,mat); CHKERRQ(ierr);
  } else {
    ierr = MatCreateMPIDense(comm,m,M,M,M,PETSC_NULL,mat); CHKERRQ(ierr); 
    /* ierr = MatCreateMPIAIJ(comm,m,m,M,M,0,0,0,0,mat); CHKERRQ(ierr); */
  }

  for ( i=0; i<M; i++ ) {
    ierr = VecSet(&zero,in); CHKERRQ(ierr);
    ierr = VecSetValues(in,1,&i,&one,INSERT_VALUES); CHKERRQ(ierr);
    ierr = VecAssemblyBegin(in); CHKERRQ(ierr);
    ierr = VecAssemblyEnd(in); CHKERRQ(ierr);

    ierr = MatMult(oldmat,in,out); CHKERRQ(ierr);
    
    ierr = VecGetArray(out,&array); CHKERRQ(ierr);
    ierr = MatSetValues(*mat,m,rows,1,&i,array,INSERT_VALUES); CHKERRQ(ierr); 
    ierr = VecRestoreArray(out,&array); CHKERRQ(ierr);

  }
  PetscFree(rows);
  ierr = VecDestroy(in); CHKERRQ(ierr);
  ierr = VecDestroy(out); CHKERRQ(ierr);
  ierr = MatAssemblyBegin(*mat,MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
  ierr = MatAssemblyEnd(*mat,MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
  PetscFunctionReturn(0);
}