!!$
!!$
!!$ MLD2P4 version 1.0
!!$ MultiLevel Domain Decomposition Parallel Preconditioners Package
!!$ based on PSBLAS (Parallel Sparse BLAS version 2.2)
!!$
!!$ (C) Copyright 2008
!!$
!!$ Salvatore Filippone University of Rome Tor Vergata
!!$ Alfredo Buttari University of Rome Tor Vergata
!!$ Pasqua D'Ambra ICAR-CNR, Naples
!!$ Daniela di Serafino Second University of Naples
!!$
!!$ Redistribution and use in source and binary forms, with or without
!!$ modification, are permitted provided that the following conditions
!!$ are met:
!!$ 1. Redistributions of source code must retain the above copyright
!!$ notice, this list of conditions and the following disclaimer.
!!$ 2. Redistributions in binary form must reproduce the above copyright
!!$ notice, this list of conditions, and the following disclaimer in the
!!$ documentation and/or other materials provided with the distribution.
!!$ 3. The name of the MLD2P4 group or the names of its contributors may
!!$ not be used to endorse or promote products derived from this
!!$ software without specific written permission.
!!$
!!$ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
!!$ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
!!$ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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!!$
! File: mld_sbaseprec_aply.f90
!
! Subroutine: mld_sbaseprec_aply
! Version: real
!
! This routine applies a base preconditioner by computing
!
! Y = beta*Y + alpha*op(K^(-1))*X,
! where
! - K is the base preconditioner, stored in prec,
! - op(K^(-1)) is K^(-1) or its transpose, according to the value of trans,
! - X and Y are vectors,
! - alpha and beta are scalars.
!
! The routine is used by mld_smlprec_aply, to apply the multilevel preconditioners,
! or directly by mld_sprec_aply, to apply the basic one-level preconditioners (diagonal,
! block-Jacobi or additive Schwarz). It also manages the case of no preconditioning.
!
!
! Arguments:
! alpha - real(psb_spk_), input.
! The scalar alpha.
! prec - type(mld_sbaseprec_type), input.
! The base preconditioner data structure containing the local part
! of the preconditioner K.
! x - real(psb_spk_), dimension(:), input.
! The local part of the vector X.
! beta - real(psb_spk_), input.
! The scalar beta.
! y - real(psb_spk_), dimension(:), input/output.
! The local part of the vector Y.
! desc_data - type(psb_desc_type), input.
! The communication descriptor associated to the matrix to be
! preconditioned.
! trans - character, optional.
! If trans='N','n' then op(K^(-1)) = K^(-1);
! if trans='T','t' then op(K^(-1)) = K^(-T) (transpose of K^(-1)).
! work - real(psb_spk_), dimension (:), optional, target.
! Workspace. Its size must be at least 4*psb_cd_get_local_cols(desc_data).
! info - integer, output.
! Error code.
!
subroutine mld_sbaseprec_aply(alpha,prec,x,beta,y,desc_data,trans,work,info)
use psb_base_mod
use mld_inner_mod, mld_protect_name => mld_sbaseprec_aply
implicit none
! Arguments
type(psb_desc_type),intent(in) :: desc_data
type(mld_sbaseprec_type), intent(in) :: prec
real(psb_spk_),intent(in) :: x(:)
real(psb_spk_),intent(inout) :: y(:)
real(psb_spk_),intent(in) :: alpha,beta
character(len=1) :: trans
real(psb_spk_),target :: work(:)
integer, intent(out) :: info
! Local variables
real(psb_spk_), pointer :: ww(:)
integer :: ictxt, np, me, err_act
integer :: n_row, int_err(5)
character(len=20) :: name, ch_err
character :: trans_
name='mld_sbaseprec_aply'
info = 0
call psb_erractionsave(err_act)
ictxt = psb_cd_get_context(desc_data)
call psb_info(ictxt, me, np)
trans_= psb_toupper(trans)
select case(trans_)
case('N','T','C')
! Ok
case default
info=40
int_err(1)=6
ch_err(2:2)=trans
goto 9999
end select
select case(prec%iprcparm(mld_smoother_type_))
case(mld_noprec_)
!
! No preconditioner
!
call psb_geaxpby(alpha,x,beta,y,desc_data,info)
case(mld_diag_)
!
! Diagonal preconditioner
!
if (size(work) >= size(x)) then
ww => work
else
allocate(ww(size(x)),stat=info)
if (info /= 0) then
call psb_errpush(4025,name,i_err=(/size(x),0,0,0,0/),a_err='real(psb_spk_)')
goto 9999
end if
end if
n_row = psb_cd_get_local_rows(desc_data)
ww(1:n_row) = x(1:n_row)*prec%d(1:n_row)
call psb_geaxpby(alpha,ww,beta,y,desc_data,info)
if (size(work) < size(x)) then
deallocate(ww,stat=info)
if (info /= 0) then
call psb_errpush(4010,name,a_err='Deallocate')
goto 9999
end if
end if
case(mld_bjac_,mld_as_)
!
! Additive Schwarz preconditioner
!
call mld_as_aply(alpha,prec,x,beta,y,desc_data,trans_,work,info)
if(info /= 0) then
info=4010
ch_err='mld_as_aply'
goto 9999
end if
case default
call psb_errpush(4001,name,a_err='Invalid mld_smoother_type_')
goto 9999
end select
call psb_erractionrestore(err_act)
return
9999 continue
call psb_errpush(info,name,i_err=int_err,a_err=ch_err)
call psb_erractionrestore(err_act)
if (err_act == psb_act_abort_) then
call psb_error()
return
end if
return
end subroutine mld_sbaseprec_aply