!!$
!!$ Parallel Sparse BLAS version 2.2
!!$ (C) Copyright 2006/2007/2008
!!$ Salvatore Filippone University of Rome Tor Vergata
!!$ Alfredo Buttari University of Rome Tor Vergata
!!$
!!$ 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.
!!$
!!$
!!$ 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_zcgstab.f90
!
! Subroutine: psb_zcgstab
! This subroutine implements the BiCG Stabilized method.
!
!
! Arguments:
!
! a - type(psb_zspmat_type) Input: sparse matrix containing A.
! prec - type(psb_zprec_type) Input: preconditioner
! b - complex,dimension(:) Input: vector containing the
! right hand side B
! x - complex,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_zcgstab(a,prec,b,x,eps,desc_a,info,itmax,iter,err,itrace,istop)
use psb_base_mod
use psb_prec_mod
use psb_krylov_mod, psb_protect_name => psb_zcgstab
Implicit None
!!$ parameters
Type(psb_zspmat_type), Intent(in) :: a
Type(psb_zprec_type), Intent(in) :: prec
Type(psb_desc_type), Intent(in) :: desc_a
Complex(Kind(1.d0)), Intent(in) :: b(:)
Complex(Kind(1.d0)), Intent(inout) :: x(:)
Real(Kind(1.d0)), Intent(in) :: eps
integer, intent(out) :: info
Integer, Optional, Intent(in) :: itmax, itrace, istop
Integer, Optional, Intent(out) :: iter
Real(Kind(1.d0)), Optional, Intent(out) :: err
!!$ Local data
Complex(Kind(1.d0)), allocatable, target :: aux(:),wwrk(:,:)
Complex(Kind(1.d0)), Pointer :: q(:),&
& r(:), p(:), v(:), s(:), t(:), z(:), f(:)
Integer :: itmax_, naux, mglob, it,itrace_,&
& np,me, n_row, n_col
integer :: debug_level, debug_unit
Integer :: itx, isvch, ictxt, err_act
Integer :: istop_
complex(Kind(1.d0)) :: alpha, beta, rho, rho_old, sigma, omega, tau
type(psb_itconv_type) :: stopdat
!!$ Integer istpb, istpe, ifctb, ifcte, imerr, irank, icomm,immb,imme
!!$ Integer mpe_log_get_event_number,mpe_Describe_state,mpe_log_event
character(len=20) :: name
character(len=*), parameter :: methdname='BiCGStab'
info = 0
name = 'psb_zcgstab'
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)
if (debug_level >= psb_debug_ext_)&
& write(debug_unit,*) me,' ',trim(name),': from psb_info',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_ = 1
Endif
call psb_chkvect(mglob,1,size(x,1),1,1,desc_a,info)
if(info /= 0) then
info=4010
call psb_errpush(info,name,a_err='psb_chkvect on X')
goto 9999
end if
call psb_chkvect(mglob,1,size(b,1),1,1,desc_a,info)
if(info /= 0) then
info=4010
call psb_errpush(info,name,a_err='psb_chkvect on B')
goto 9999
end if
naux=6*n_col
allocate(aux(naux),stat=info)
if (info==0) call psb_geall(wwrk,desc_a,info,n=8)
if (info==0) call psb_geasb(wwrk,desc_a,info)
if (info /= 0) then
info=4011
call psb_errpush(info,name)
goto 9999
End If
Q => WWRK(:,1)
R => WWRK(:,2)
P => WWRK(:,3)
V => WWRK(:,4)
F => WWRK(:,5)
S => WWRK(:,6)
T => WWRK(:,7)
Z => WWRK(:,8)
if (present(itmax)) then
itmax_ = itmax
else
itmax_ = 1000
endif
if (present(itrace)) then
itrace_ = itrace
else
itrace_ = 0
end if
! Ensure global coherence for convergence checks.
call psb_set_coher(ictxt,isvch)
itx = 0
call psb_init_conv(methdname,istop_,itrace_,itmax_,a,b,eps,desc_a,stopdat,info)
if (info /= 0) Then
call psb_errpush(4011,name)
goto 9999
End If
restart: Do
!!$
!!$ r0 = b-Ax0
!!$
if (itx >= itmax_) exit restart
it = 0
call psb_geaxpby(zone,b,zzero,r,desc_a,info)
if (info == 0) call psb_spmm(-zone,a,x,zone,r,desc_a,info,work=aux)
if (info == 0) call psb_geaxpby(zone,r,zzero,q,desc_a,info)
if (info /= 0) then
info=4011
call psb_errpush(info,name)
goto 9999
end if
rho = zzero
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' On entry to AMAX: B: ',Size(b)
! Perhaps we already satisfy the convergence criterion...
if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart
if (info /= 0) Then
call psb_errpush(4011,name)
goto 9999
End If
iteration: Do
it = it + 1
itx = itx + 1
If (debug_level >= psb_debug_ext_)&
& write(debug_unit,*) me,' ',trim(name),&
& ' Iteration: ',itx
rho_old = rho
rho = psb_gedot(q,r,desc_a,info)
if (rho==zzero) then
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' Iteration breakdown R',rho
exit iteration
endif
if (it==1) then
call psb_geaxpby(zone,r,zzero,p,desc_a,info)
else
beta = (rho/rho_old)*(alpha/omega)
call psb_geaxpby(-omega,v,zone,p,desc_a,info)
if (info == 0) call psb_geaxpby(zone,r,beta,p,desc_a,info)
end if
if (info == 0) call psb_precaply(prec,p,f,desc_a,info,work=aux)
if (info == 0) call psb_spmm(zone,a,f,zzero,v,desc_a,info,&
& work=aux)
if (info == 0) sigma = psb_gedot(q,v,desc_a,info)
if (info /= 0) then
call psb_errpush(4010,name,a_err='First step')
goto 9999
end if
if (sigma==zzero) then
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' Iteration breakdown S1', sigma
exit iteration
endif
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' SIGMA:',sigma
alpha = rho/sigma
call psb_geaxpby(zone,r,zzero,s,desc_a,info)
if (info == 0) call psb_geaxpby(-alpha,v,zone,s,desc_a,info)
if (info == 0) call psb_precaply(prec,s,z,desc_a,info,work=aux)
if (info == 0) call psb_spmm(zone,a,z,zzero,t,desc_a,info,&
& work=aux)
if (info /= 0) then
call psb_errpush(4010,name,a_err='Second step ')
goto 9999
end if
sigma = psb_gedot(t,t,desc_a,info)
if (sigma==zzero) then
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' Iteration breakdown S2', sigma
exit iteration
endif
tau = psb_gedot(t,s,desc_a,info)
omega = tau/sigma
if (omega==zzero) then
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' Iteration breakdown O',omega
exit iteration
endif
if (info == 0) call psb_geaxpby(alpha,f,zone,x,desc_a,info)
if (info == 0) call psb_geaxpby(omega,z,zone,x,desc_a,info)
if (info == 0) call psb_geaxpby(zone,s,zzero,r,desc_a,info)
if (info == 0) call psb_geaxpby(-omega,t,zone,r,desc_a,info)
if (info /= 0) then
call psb_errpush(4010,name,a_err='X update ')
goto 9999
end if
if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart
if (info /= 0) Then
call psb_errpush(4011,name)
goto 9999
End If
end do iteration
end do restart
call psb_end_conv(methdname,itx,desc_a,stopdat,info,err,iter)
deallocate(aux,stat=info)
if (info == 0) call psb_gefree(wwrk,desc_a,info)
if (info/=0) 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(ictxt)
return
end if
return
End Subroutine psb_zcgstab