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psblas3/krylov/psb_scg.F90

335 lines
12 KiB
Fortran

!
! Parallel Sparse BLAS version 3.5
! (C) Copyright 2006-2018
! Salvatore Filippone
! Alfredo Buttari
!
! 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 Input: vector containing the
! right hand side B
! x(:) - real 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|/(|a||x|+|b|); here the iteration is
! stopped when |r| <= eps * (|a||x|+|b|)
! 2: err = |r|/|b|; here the iteration is
! stopped when |r| <= eps * |b|
! where r is the (preconditioned, recursive
! estimate of) residual.
!
!
subroutine psb_scg_vect(a,prec,b,x,eps,desc_a,info,&
& itmax,iter,err,itrace,istop,cond)
use psb_base_mod
use psb_prec_mod
use psb_s_krylov_conv_mod
use psb_krylov_mod
implicit none
type(psb_sspmat_type), intent(in) :: a
Type(psb_desc_type), Intent(in) :: desc_a
class(psb_sprec_type), intent(inout) :: prec
type(psb_s_vect_type), Intent(inout) :: b
type(psb_s_vect_type), Intent(inout) :: x
Real(psb_spk_), Intent(in) :: eps
integer(psb_ipk_), intent(out) :: info
integer(psb_ipk_), Optional, Intent(in) :: itmax, itrace, istop
integer(psb_ipk_), Optional, Intent(out) :: iter
Real(psb_spk_), Optional, Intent(out) :: err,cond
! = Local data
real(psb_spk_), allocatable, target :: aux(:),td(:),tu(:),eig(:),ewrk(:)
integer(psb_mpk_), allocatable :: ibl(:), ispl(:), iwrk(:)
type(psb_s_vect_type), allocatable, target :: wwrk(:)
type(psb_s_vect_type), pointer :: q, p, r, z, w
real(psb_spk_) :: alpha, beta, rho, rho_old, sigma,alpha_old,beta_old
integer(psb_ipk_) :: itmax_, istop_, naux, it, itx, itrace_,&
& n_col, n_row,err_act, ieg,nspl, istebz
integer(psb_lpk_) :: mglob
integer(psb_ipk_) :: debug_level, debug_unit
type(psb_ctxt_type) :: ctxt
integer(psb_ipk_) :: np, me
real(psb_dpk_) :: derr
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()
ctxt = desc_a%get_context()
call psb_info(ctxt, me, np)
if (.not.allocated(b%v)) then
info = psb_err_invalid_vect_state_
call psb_errpush(info,name)
goto 9999
endif
if (.not.allocated(x%v)) then
info = psb_err_invalid_vect_state_
call psb_errpush(info,name)
goto 9999
endif
mglob = desc_a%get_global_rows()
n_row = desc_a%get_local_rows()
n_col = desc_a%get_local_cols()
if (present(istop)) then
istop_ = istop
else
istop_ = 2
endif
call psb_chkvect(mglob,lone,x%get_nrows(),lone,lone,desc_a,info)
if (info == psb_success_)&
& call psb_chkvect(mglob,lone,b%get_nrows(),lone,lone,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=5_psb_ipk_)
if (info == psb_success_) call psb_geasb(wwrk,desc_a,info,mold=x%v,scratch=.true.)
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
alpha = szero
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,x,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 == psb_root_) 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/))
info=psb_err_from_subroutine_ai_
goto 9999
end if
cond = eig(ieg)/eig(1)
#else
cond = szero
#endif
info=psb_success_
end if
call psb_bcast(ctxt,cond)
end if
call psb_end_conv(methdname,itx,desc_a,stopdat,info,derr,iter)
if (present(err)) err = derr
if (info == psb_success_) call psb_gefree(wwrk,desc_a,info)
if (info == psb_success_) deallocate(aux,stat=info)
if (info /= psb_success_) then
call psb_errpush(info,name)
goto 9999
end if
call psb_erractionrestore(err_act)
return
9999 call psb_error_handler(err_act)
return
end subroutine psb_scg_vect