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psblas3/krylov/psb_scg.F90

331 lines
12 KiB
Fortran

!!$
!!$ Parallel Sparse BLAS version 3.0
!!$ (C) Copyright 2006, 2007, 2008, 2009, 2010
!!$ Salvatore Filippone University of Rome Tor Vergata
!!$ Alfredo Buttari CNRS-IRIT, Toulouse
!!$
!!$ 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 PSBLAS 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
!!$ PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
!!$ BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
!!$ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
!!$ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
!!$ INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
!!$ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
!!$ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
!!$ POSSIBILITY OF SUCH DAMAGE.
!!$
!!$
! File: psb_scg.f90
!!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
!!$ C C
!!$ C References: C
!!$ C [1] Duff, I., Marrone, M., Radicati, G., and Vittoli, C. C
!!$ C Level 3 basic linear algebra subprograms for sparse C
!!$ C matrices: a user level interface C
!!$ C ACM Trans. Math. Softw., 23(3), 379-401, 1997. C
!!$ C C
!!$ C C
!!$ C [2] S. Filippone, M. Colajanni C
!!$ C PSBLAS: A library for parallel linear algebra C
!!$ C computation on sparse matrices C
!!$ C ACM Trans. on Math. Softw., 26(4), 527-550, Dec. 2000. C
!!$ C C
!!$ C [3] M. Arioli, I. Duff, M. Ruiz C
!!$ C Stopping criteria for iterative solvers C
!!$ C SIAM J. Matrix Anal. Appl., Vol. 13, pp. 138-144, 1992 C
!!$ C C
!!$ C C
!!$ C [4] R. Barrett et al C
!!$ C Templates for the solution of linear systems C
!!$ C SIAM, 1993
!!$ C C
!!$ C C
!!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
! File: psb_scg.f90
!
! Subroutine: psb_scg
! This subroutine implements the Conjugate Gradient method.
!
!
! Arguments:
!
! a - type(psb_sspmat_type) Input: sparse matrix containing A.
! prec - class(psb_sprec_type) Input: preconditioner
! b - real,dimension(:) Input: vector containing the
! right hand side B
! x - real,dimension(:) Input/Output: vector containing the
! initial guess and final solution X.
! eps - real Input: Stopping tolerance; the iteration is
! stopped when the error estimate |err| <= eps
! desc_a - type(psb_desc_type). Input: The communication descriptor.
! info - integer. Output: Return code
!
! itmax - integer(optional) Input: maximum number of iterations to be
! performed.
! iter - integer(optional) Output: how many iterations have been
! performed.
! performed.
! err - real (optional) Output: error estimate on exit. If the
! denominator of the estimate is exactly
! 0, it is changed into 1.
! itrace - integer(optional) Input: print an informational message
! with the error estimate every itrace
! iterations
! istop - integer(optional) Input: stopping criterion, or how
! to estimate the error.
! 1: err = |r|/|b|; here the iteration is
! stopped when |r| <= eps * |b|
! 2: err = |r|/(|a||x|+|b|); here the iteration is
! stopped when |r| <= eps * (|a||x|+|b|)
! where r is the (preconditioned, recursive
! estimate of) residual.
!
!
subroutine psb_scg(a,prec,b,x,eps,desc_a,info,itmax,iter,err,itrace,istop,cond)
use psb_base_mod
use psb_prec_mod
use psb_inner_krylov_mod
use psb_krylov_mod
implicit none
!!$ Parameters
Type(psb_sspmat_type), Intent(in) :: a
class(psb_sprec_type), Intent(in) :: prec
Type(psb_desc_type), Intent(in) :: desc_a
Real(psb_spk_), Intent(in) :: b(:)
Real(psb_spk_), Intent(inout) :: x(:)
Real(psb_spk_), Intent(in) :: eps
integer, intent(out) :: info
Integer, Optional, Intent(in) :: itmax, itrace, istop
Integer, Optional, Intent(out) :: iter
Real(psb_spk_), Optional, Intent(out) :: err,cond
!!$ Local data
real(psb_spk_), allocatable, target :: aux(:), wwrk(:,:), td(:),tu(:),eig(:),ewrk(:)
integer, allocatable :: ibl(:), ispl(:), iwrk(:)
real(psb_spk_), pointer :: q(:), p(:), r(:), z(:), w(:)
real(psb_spk_) :: alpha, beta, rho, rho_old, sigma,alpha_old,beta_old
integer :: itmax_, istop_, naux, mglob, it, itx, itrace_,&
& np,me, n_col, isvch, ictxt, n_row,err_act, int_err(5), ieg,nspl, istebz
real(psb_dpk_) :: derr
integer :: debug_level, debug_unit
type(psb_itconv_type) :: stopdat
logical :: do_cond
character(len=20) :: name
character(len=*), parameter :: methdname='CG'
info = psb_success_
name = 'psb_scg'
call psb_erractionsave(err_act)
debug_unit = psb_get_debug_unit()
debug_level = psb_get_debug_level()
ictxt = psb_cd_get_context(desc_a)
call psb_info(ictxt, me, np)
mglob = psb_cd_get_global_rows(desc_a)
n_row = psb_cd_get_local_rows(desc_a)
n_col = psb_cd_get_local_cols(desc_a)
if (present(istop)) then
istop_ = istop
else
istop_ = 2
endif
call psb_chkvect(mglob,1,size(x,1),1,1,desc_a,info)
if (info == psb_success_) call psb_chkvect(mglob,1,size(b,1),1,1,desc_a,info)
if(info /= psb_success_) then
info=psb_err_from_subroutine_
call psb_errpush(info,name,a_err='psb_chkvect on X/B')
goto 9999
end if
naux=4*n_col
allocate(aux(naux), stat=info)
if (info == psb_success_) call psb_geall(wwrk,desc_a,info,n=psb_err_invalid_input_)
if (info == psb_success_) call psb_geasb(wwrk,desc_a,info)
if (info /= psb_success_) then
info=psb_err_from_subroutine_non_
call psb_errpush(info,name)
goto 9999
end if
p => wwrk(:,1)
q => wwrk(:,2)
r => wwrk(:,3)
z => wwrk(:,4)
w => wwrk(:,5)
if (present(itmax)) then
itmax_ = itmax
else
itmax_ = 1000
endif
if (present(itrace)) then
itrace_ = itrace
else
itrace_ = 0
end if
do_cond=present(cond)
if (do_cond) then
istebz = 0
allocate(td(itmax_),tu(itmax_), eig(itmax_),&
& ibl(itmax_),ispl(itmax_),iwrk(3*itmax_),ewrk(4*itmax_),&
& stat=info)
if (info /= psb_success_) then
info=psb_err_from_subroutine_non_
call psb_errpush(info,name)
goto 9999
end if
end if
itx=0
! Ensure global coherence for convergence checks.
call psb_set_coher(ictxt,isvch)
restart: do
!!$
!!$ r0 = b-Ax0
!!$
if (itx>= itmax_) exit restart
it = 0
call psb_geaxpby(sone,b,szero,r,desc_a,info)
if (info == psb_success_) call psb_spmm(-sone,a,x,sone,r,desc_a,info,work=aux)
if (info /= psb_success_) then
info=psb_err_from_subroutine_non_
call psb_errpush(info,name)
goto 9999
end if
rho = szero
call psb_init_conv(methdname,istop_,itrace_,itmax_,a,b,eps,desc_a,stopdat,info)
if (info /= psb_success_) Then
call psb_errpush(psb_err_from_subroutine_non_,name)
goto 9999
End If
iteration: do
it = it + 1
itx = itx + 1
call prec%apply(r,z,desc_a,info,work=aux)
rho_old = rho
rho = psb_gedot(r,z,desc_a,info)
if (it == 1) then
call psb_geaxpby(sone,z,szero,p,desc_a,info)
else
if (rho_old == szero) then
if (debug_level >= psb_debug_ext_)&
& write(debug_unit,*) me,' ',trim(name),&
& ': CG Iteration breakdown rho'
exit iteration
endif
beta = rho/rho_old
call psb_geaxpby(sone,z,beta,p,desc_a,info)
end if
call psb_spmm(sone,a,p,szero,q,desc_a,info,work=aux)
sigma = psb_gedot(p,q,desc_a,info)
if (sigma == szero) then
if (debug_level >= psb_debug_ext_)&
& write(debug_unit,*) me,' ',trim(name),&
& ': CG Iteration breakdown sigma'
exit iteration
endif
alpha_old = alpha
alpha = rho/sigma
if (do_cond) then
istebz = istebz + 1
if (istebz == 1) then
td(istebz) = sone/alpha
else
td(istebz) = sone/alpha + beta/alpha_old
tu(istebz-1) = sqrt(beta)/alpha_old
end if
end if
call psb_geaxpby(alpha,p,sone,x,desc_a,info)
call psb_geaxpby(-alpha,q,sone,r,desc_a,info)
if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart
if (info /= psb_success_) Then
call psb_errpush(psb_err_from_subroutine_non_,name)
goto 9999
End If
end do iteration
end do restart
if (do_cond) then
if (me == 0) then
#if defined(HAVE_LAPACK)
call sstebz('A','E',istebz,szero,szero,0,0,-sone,td,tu,&
& ieg,nspl,eig,ibl,ispl,ewrk,iwrk,info)
if (info < 0) then
call psb_errpush(psb_err_from_subroutine_ai_,name,a_err='sstebz',i_err=(/info,0,0,0,0/))
info = psb_err_from_subroutine_ai_
goto 9999
end if
cond = eig(ieg)/eig(1)
#else
cond = -1.0
#endif
info = psb_success_
end if
call psb_bcast(ictxt,cond,root=0)
end if
call psb_end_conv(methdname,itx,desc_a,stopdat,info,derr,iter)
if (present(err)) then
err = derr
end if
call psb_gefree(wwrk,desc_a,info)
if (info /= psb_success_) then
call psb_errpush(info,name)
goto 9999
end if
! restore external global coherence behaviour
call psb_restore_coher(ictxt,isvch)
call psb_erractionrestore(err_act)
return
9999 continue
call psb_erractionrestore(err_act)
if (err_act == psb_act_abort_) then
call psb_error()
return
end if
return
end subroutine psb_scg