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/*

   Subroutines related to special Vecs that share a common contiguous storage.

   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

   SLEPc - Scalable Library for Eigenvalue Problem Computations

   Copyright (c) 2002-2010, Universidad Politecnica de Valencia, Spain

   This file is part of SLEPc.

   SLEPc is free software: you can redistribute it and/or modify it under  the

   terms of version 3 of the GNU Lesser General Public License as published by

   the Free Software Foundation.

   SLEPc  is  distributed in the hope that it will be useful, but WITHOUT  ANY

   WARRANTY;  without even the implied warranty of MERCHANTABILITY or  FITNESS

   FOR  A  PARTICULAR PURPOSE. See the GNU Lesser General Public  License  for

   more details.

   You  should have received a copy of the GNU Lesser General  Public  License

   along with SLEPc. If not, see <http://www.gnu.org/licenses/>.

   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

*/

#include <private/vecimplslepc.h>            /*I "slepcvec.h" I*/

#include <petscblaslapack.h>

PetscLogEvent SLEPC_UpdateVectors = 0,SLEPC_VecMAXPBY = 0;

#undef __FUNCT__

#define __FUNCT__ "Vecs_ContiguousDestroy"

/*

  Frees the array of the contiguous vectors when all vectors have been destroyed.

*/

static PetscErrorCode Vecs_ContiguousDestroy(void *ctx)

{

  PetscErrorCode  ierr;

  Vecs_Contiguous *vc = (Vecs_Contiguous*)ctx;

  PetscFunctionBegin;

  ierr = PetscFree(vc->array);CHKERRQ(ierr);

  ierr = PetscFree(vc);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__

#define __FUNCT__ "VecDuplicateVecs_Contiguous"

/*

  Version of VecDuplicateVecs that sets contiguous storage.

*/

static PetscErrorCode VecDuplicateVecs_Contiguous(Vec v,PetscInt m,Vec *V[])

{

  PetscErrorCode  ierr;

  PetscInt        i,nloc;

  PetscScalar     *pV;

  PetscContainer  container;

  Vecs_Contiguous *vc;

  PetscFunctionBegin;

  /* Allocate array */

  ierr = VecGetLocalSize(v,&nloc);CHKERRQ(ierr);

  ierr = PetscMalloc(m*nloc*sizeof(PetscScalar),&pV);CHKERRQ(ierr);

  /* Create container */

  ierr = PetscNew(Vecs_Contiguous,&vc);CHKERRQ(ierr);

  vc->nvecs = m;

  vc->array = pV;

  ierr = PetscContainerCreate(((PetscObject)v)->comm,&container);CHKERRQ(ierr);

  ierr = PetscContainerSetPointer(container,vc);CHKERRQ(ierr);

  ierr = PetscContainerSetUserDestroy(container,Vecs_ContiguousDestroy);CHKERRQ(ierr);

  /* Create vectors */

  ierr = PetscMalloc(m*sizeof(Vec),V);CHKERRQ(ierr);

  for (i=0;i<m;i++) {

    ierr = VecCreateMPIWithArray(((PetscObject)v)->comm,nloc,PETSC_DECIDE,pV+i*nloc,*V+i);CHKERRQ(ierr);

    ierr = PetscObjectCompose((PetscObject)*(*V+i),"contiguous",(PetscObject)container);CHKERRQ(ierr);

  }

  ierr = PetscContainerDestroy(&container);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "SlepcVecSetTemplate"

/*@

   SlepcVecSetTemplate - Sets a vector as a template for contiguous storage.

   Collective on Vec

   Input Parameters:

.  v - the vector

   Note:

   Once this function is called, subsequent calls to VecDuplicateVecs()

   with this vector will use a special version that generates vectors with

   contiguous storage, that is, the array of values of V[1] immediately

   follows the array of V[0], and so on.

   Level: developer

@*/

PetscErrorCode SlepcVecSetTemplate(Vec v)

{

  PetscErrorCode ierr;

  PetscBool      flg;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(v,VEC_CLASSID,1);

  ierr = PetscTypeCompareAny((PetscObject)v,&flg,VECSEQ,VECMPI,"");CHKERRQ(ierr);

  if (!flg) SETERRQ(((PetscObject)v)->comm,PETSC_ERR_SUP,"Only available for standard vectors (VECSEQ or VECMPI)");

  v->ops->duplicatevecs = VecDuplicateVecs_Contiguous;

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "SlepcMatGetVecsTemplate"

/*@

   SlepcMatGetVecsTemplate - Get vectors compatible with a matrix,

   i.e. with the same parallel layout, and mark them as templates

   for contiguous storage.

   Collective on Mat

   Input Parameter:

.  mat - the matrix

   Output Parameters:

+  right - (optional) vector that the matrix can be multiplied against

-  left  - (optional) vector that the matrix vector product can be stored in

   Options Database Keys:

.  -slepc_non_contiguous - Disable contiguous vector storage

   Notes:

   Use -slepc_non_contiguous to disable contiguous storage throughout SLEPc.

   Contiguous storage is currently also disabled in AIJCUSP matrices.

   Level: developer

.seealso: SlepcVecSetTemplate()

@*/

PetscErrorCode SlepcMatGetVecsTemplate(Mat mat,Vec *right,Vec *left)

{

  PetscErrorCode ierr;

  PetscBool      flg;

  Vec            v;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(mat,MAT_CLASSID,1);

  PetscValidType(mat,1);

  ierr = MatGetVecs(mat,right,left);CHKERRQ(ierr);

  v = right? *right: *left;

  ierr = PetscTypeCompareAny((PetscObject)v,&flg,VECSEQ,VECMPI,"");CHKERRQ(ierr);

  if (!flg) PetscFunctionReturn(0);

  ierr = PetscOptionsHasName(PETSC_NULL,"-slepc_non_contiguous",&flg);CHKERRQ(ierr);

  if (!flg) {

    if (right) { ierr = SlepcVecSetTemplate(*right);CHKERRQ(ierr); }

    if (left) { ierr = SlepcVecSetTemplate(*left);CHKERRQ(ierr); }

  }

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "SlepcUpdateVectors"

/*@

   SlepcUpdateVectors - Update a set of vectors V as V(:,s:e-1) = V*Q(:,s:e-1).

   Not Collective

   Input parameters:

+  n      - number of vectors in V

.  s      - first column of V to be overwritten

.  e      - first column of V not to be overwritten

.  Q      - matrix containing the coefficients of the update

.  ldq    - leading dimension of Q

-  qtrans - flag indicating if Q is to be transposed

   Input/Output parameter:

.  V      - set of vectors

   Notes:

   This function computes V(:,s:e-1) = V*Q(:,s:e-1), that is, given a set of

   vectors V, columns from s to e-1 are overwritten with columns from s to

   e-1 of the matrix-matrix product V*Q.

   Matrix V is represented as an array of Vec, whereas Q is represented as

   a column-major dense array of leading dimension ldq. Only columns s to e-1

   of Q are referenced.

   If qtrans=PETSC_TRUE, the operation is V*Q'.

   This routine is implemented with a call to BLAS, therefore V is an array

   of Vec which have the data stored contiguously in memory as a Fortran matrix.

   PETSc does not create such arrays by default.

   Level: developer

@*/

PetscErrorCode SlepcUpdateVectors(PetscInt n_,Vec *V,PetscInt s,PetscInt e,const PetscScalar *Q,PetscInt ldq_,PetscBool qtrans)

{

  PetscErrorCode ierr;

  PetscFunctionBegin;

  ierr = SlepcUpdateStrideVectors(n_,V,s,1,e,Q,ldq_,qtrans);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "SlepcUpdateStrideVectors"

/*@

   SlepcUpdateStrideVectors - Update a set of vectors V as

   V(:,s:d:e-1) = V*Q(:,s:e-1).

   Not Collective

   Input parameters:

+  n      - number of vectors in V

.  s      - first column of V to be overwritten

.  d      - stride

.  e      - first column of V not to be overwritten

.  Q      - matrix containing the coefficients of the update

.  ldq    - leading dimension of Q

-  qtrans - flag indicating if Q is to be transposed

   Input/Output parameter:

.  V      - set of vectors

   Notes:

   This function computes V(:,s:d:e-1) = V*Q(:,s:e-1), that is, given a set

   of vectors V, columns from s to e-1 are overwritten with columns from s to

   e-1 of the matrix-matrix product V*Q.

   Matrix V is represented as an array of Vec, whereas Q is represented as

   a column-major dense array of leading dimension ldq. Only columns s to e-1

   of Q are referenced.

   If qtrans=PETSC_TRUE, the operation is V*Q'.

   This routine is implemented with a call to BLAS, therefore V is an array

   of Vec which have the data stored contiguously in memory as a Fortran matrix.

   PETSc does not create such arrays by default.

   Level: developer

@*/

PetscErrorCode SlepcUpdateStrideVectors(PetscInt n_,Vec *V,PetscInt s,PetscInt d,PetscInt e,const PetscScalar *Q,PetscInt ldq_,PetscBool qtrans)

{

  PetscErrorCode ierr;

  PetscInt       l;

  PetscBLASInt   i,j,k,bs=64,m,n,ldq,ls,ld;

  PetscScalar    *pv,*pw,*pq,*work,*pwork,one=1.0,zero=0.0;

  const char     *qt;

  PetscFunctionBegin;

  n = PetscBLASIntCast(n_/d);

  ldq = PetscBLASIntCast(ldq_);

  m = (e-s)/d;

  if (m==0) PetscFunctionReturn(0);

  PetscValidIntPointer(Q,5);

  if (m<0 || n<0 || s<0 || m>n) SETERRQ(((PetscObject)*V)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Index argument out of range");

  ierr = PetscLogEventBegin(SLEPC_UpdateVectors,0,0,0,0);CHKERRQ(ierr);

  ierr = VecGetLocalSize(V[0],&l);CHKERRQ(ierr);

  ls = PetscBLASIntCast(l);

  ld = ls*PetscBLASIntCast(d);

  ierr = VecGetArray(V[0],&pv);CHKERRQ(ierr);

  if (qtrans) {

    pq = (PetscScalar*)Q+s;

    qt = "T";

  } else {

    pq = (PetscScalar*)Q+s*ldq;

    qt = "N";

  }

  ierr = PetscMalloc(sizeof(PetscScalar)*bs*m,&work);CHKERRQ(ierr);

  k = ls % bs;

  if (k) {

    BLASgemm_("N",qt,&k,&m,&n,&one,pv,&ld,pq,&ldq,&zero,work,&k);

    for (j=0;j<m;j++) {

      pw = pv+(s+j)*ld;

      pwork = work+j*k;

      for (i=0;i<k;i++) {

        *pw++ = *pwork++;

      }

    }        

  }

  for (;k<ls;k+=bs) {

    BLASgemm_("N",qt,&bs,&m,&n,&one,pv+k,&ld,pq,&ldq,&zero,work,&bs);

    for (j=0;j<m;j++) {

      pw = pv+(s+j)*ld+k;

      pwork = work+j*bs;

      for (i=0;i<bs;i++) {

        *pw++ = *pwork++;

      }

    }

  }

  ierr = VecRestoreArray(V[0],&pv);CHKERRQ(ierr);

  ierr = PetscFree(work);CHKERRQ(ierr);

  ierr = PetscLogFlops(m*n*2.0*ls);CHKERRQ(ierr);

  ierr = PetscLogEventEnd(SLEPC_UpdateVectors,0,0,0,0);CHKERRQ(ierr);

  PetscFunctionReturn(0);

}

#undef __FUNCT__  

#define __FUNCT__ "SlepcVecMAXPBY"

/*@

   SlepcVecMAXPBY - Computes y = beta*y + sum alpha*a[j]*x[j]

   Logically Collective on Vec

   Input parameters:

+  beta   - scalar beta

.  alpha  - scalar alpha

.  nv     - number of vectors in x and scalars in a

.  a      - array of scalars

-  x      - set of vectors

   Input/Output parameter:

.  y      - the vector to update

   Notes:

   If x are Vec's with contiguous storage, then the operation is done

   through a call to BLAS. Otherwise, VecMAXPY() is called.

   Level: developer

.seealso: SlepcVecSetTemplate()

@*/

PetscErrorCode SlepcVecMAXPBY(Vec y,PetscScalar beta,PetscScalar alpha,PetscInt nv,const PetscScalar a[],Vec x[])

{

  PetscErrorCode    ierr;

  PetscBLASInt      n,m,one=1;

  PetscScalar       *py;

  const PetscScalar *px;

  PetscContainer    container;

  Vec               z;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(y,VEC_CLASSID,1);

  if (!nv || !(y)->map->n) PetscFunctionReturn(0);

  if (nv < 0) SETERRQ1(((PetscObject)y)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Number of vectors (given %D) cannot be negative",nv);

  PetscValidLogicalCollectiveScalar(y,alpha,2);

  PetscValidLogicalCollectiveScalar(y,beta,3);

  PetscValidLogicalCollectiveInt(y,nv,4);

  PetscValidScalarPointer(a,5);

  PetscValidPointer(x,6);

  PetscValidHeaderSpecific(*x,VEC_CLASSID,6);

  PetscValidType(y,1);

  PetscValidType(*x,6);

  PetscCheckSameTypeAndComm(y,1,*x,6);

  if ((*x)->map->N != (y)->map->N) SETERRQ(((PetscObject)y)->comm,PETSC_ERR_ARG_INCOMP,"Incompatible vector global lengths");

  if ((*x)->map->n != (y)->map->n) SETERRQ(((PetscObject)y)->comm,PETSC_ERR_ARG_INCOMP,"Incompatible vector local lengths");

  ierr = PetscObjectQuery((PetscObject)(x[0]),"contiguous",(PetscObject*)&container);CHKERRQ(ierr);

  if (container) {

    /* assume x Vecs are contiguous, use BLAS calls */

    ierr = PetscLogEventBegin(SLEPC_VecMAXPBY,*x,y,0,0);CHKERRQ(ierr);

    ierr = VecGetArray(y,&py);CHKERRQ(ierr);

    ierr = VecGetArrayRead(*x,&px);CHKERRQ(ierr);

    n = PetscBLASIntCast(nv);

    m = PetscBLASIntCast((y)->map->n);

    BLASgemv_("N",&m,&n,&alpha,px,&m,a,&one,&beta,py,&one);

    ierr = VecRestoreArray(y,&py);CHKERRQ(ierr);

    ierr = VecRestoreArrayRead(*x,&px);CHKERRQ(ierr);

    ierr = PetscLogFlops(nv*2*(y)->map->n);CHKERRQ(ierr);

    ierr = PetscLogEventEnd(SLEPC_VecMAXPBY,*x,y,0,0);CHKERRQ(ierr);

  } else {

    /* use regular Vec operations */

    ierr = VecDuplicate(y,&z);CHKERRQ(ierr);

    ierr = VecCopy(y,z);CHKERRQ(ierr);

    ierr = VecMAXPY(y,nv,a,x);CHKERRQ(ierr);

    ierr = VecAXPBY(y,beta-alpha,alpha,z);CHKERRQ(ierr);

    ierr = VecDestroy(&z);CHKERRQ(ierr);

  }

  PetscFunctionReturn(0);

}