!!$
!!$ Parallel Sparse BLAS v2.0
!!$ (C) Copyright 2006 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_dcgstab.f90
!
! Subroutine: psb_dcgstab
! This subroutine implements the CG Stabilized method.
!
! Parameters:
! a - type(<psb_dspmat_type>). The sparse matrix containing A.
! prec - type(<psb_prec_type>). The data structure containing the preconditioner.
! b - real,dimension(:). The right hand side.
! x - real,dimension(:). The vector of unknowns.
! eps - real. The error tolerance.
! desc_a - type(<psb_desc_type>). The communication descriptor.
! info - integer. Eventually returns an error code.
! itmax - integer(optional). The maximum number of iterations.
! iter - integer(optional). The number of iterations performed.
! err - real(optional). The error on return.
! itrace - integer(optional). The unit to write messages onto.
! istop - integer(optional). The stopping criterium.
!
Subroutine psb_dcgstab(a,prec,b,x,eps,desc_a,info,&
&itmax,iter,err,itrace, istop)
use psb_base_mod
use psb_prec_mod
Implicit None
!!$ parameters
Type(psb_dspmat_type), Intent(in) :: a
Type(psb_dprec_type), Intent(in) :: prec
Type(psb_desc_type), Intent(in) :: desc_a
Real(Kind(1.d0)), Intent(in) :: b(:)
Real(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
Real(Kind(1.d0)), allocatable, target :: aux(:),wwrk(:,:)
Real(Kind(1.d0)), Pointer :: q(:),&
& r(:), p(:), v(:), s(:), t(:), z(:), f(:)
Real(Kind(1.d0)) :: rerr
Integer :: litmax, naux, m, mglob, it,itrace_,&
& np,me, n_row, n_col
Character ::diagl, diagu
Logical, Parameter :: debug = .false.
Logical, Parameter :: exchange=.True., noexchange=.False., debug1 = .False.
Integer, Parameter :: irmax = 8
Integer :: itx, i, isvch, ictxt, err_act, int_err(5),ii
Integer :: istop_
Real(Kind(1.d0)) :: alpha, beta, rho, rho_old, rni, xni, bni, ani,&
& sigma, omega, tau, rn0, bn2
#ifdef MPE_KRYLOV
Integer istpb, istpe, ifctb, ifcte, imerr, irank, icomm,immb,imme
Integer mpe_log_get_event_number,mpe_Describe_state,mpe_log_event
#endif
character(len=20) :: name
info = 0
name = 'psb_dcgstab'
call psb_erractionsave(err_act)
If (debug) Write(*,*) 'Entering PSB_DCGSTAB',present(istop)
ictxt = psb_cd_get_context(desc_a)
call psb_info(ictxt, me, np)
if (debug) write(*,*) 'PSB_DCGSTAB: From GRIDINFO',np,me
#ifdef MPE_KRYLOV
call psb_get_mpicomm(ictxt,icomm)
call psb_get_rank(irank,ictxt,me)
istpb = mpe_log_get_event_number()
istpe = mpe_log_get_event_number()
ifctb = mpe_log_get_event_number()
ifcte = mpe_log_get_event_number()
immb = mpe_log_get_event_number()
imme = mpe_log_get_event_number()
if (irank==0) then
info = mpe_describe_state(istpb,istpe,"Solver","WhiteSmoke")
info = mpe_describe_state(ifctb,ifcte,"PREC","SteelBlue")
info = mpe_describe_state(immb,imme,"SPMM","DarkOrange")
endif
#endif
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
!
! ISTOP_ = 1: Normwise backward error, infinity norm
! ISTOP_ = 2: ||r||/||b|| norm 2
!
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( istpb, 0, "st CGSTAB" )
#endif
if ((istop_ < 1 ).or.(istop_ > 2 ) ) then
write(0,*) 'psb_bicgstab: invalid istop',istop_
info=5001
int_err(1)=istop_
err=info
call psb_errpush(info,name,i_err=int_err)
goto 9999
endif
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
litmax = itmax
Else
litmax = 1000
Endif
If (Present(itrace)) Then
itrace_ = itrace
Else
itrace_ = 0
End If
diagl = 'U'
diagu = 'U'
! Ensure global coherence for convergence checks.
call psb_set_coher(ictxt,isvch)
itx = 0
If (istop_ == 1) Then
ani = psb_spnrmi(a,desc_a,info)
bni = psb_geamax(b,desc_a,info)
Else If (istop_ == 2) Then
bn2 = psb_genrm2(b,desc_a,info)
Endif
if (info /= 0) Then
info=4011
call psb_errpush(info,name)
goto 9999
End If
restart: Do
!!$
!!$ r0 = b-Ax0
!!$
If (itx >= litmax) Exit restart
it = 0
Call psb_geaxpby(done,b,dzero,r,desc_a,info)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( immb, 0, "st SPMM" )
#endif
Call psb_spmm(-done,a,x,done,r,desc_a,info,work=aux)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( imme, 0, "ed SPMM" )
#endif
Call psb_geaxpby(done,r,dzero,q,desc_a,info)
if (info /= 0) Then
info=4011
call psb_errpush(info,name)
goto 9999
End If
rho = dzero
If (debug) Write(*,*) 'On entry to AMAX: B: ',Size(b)
!
! Must always provide norm of R into RNI below for first check on
! residual
!
If (istop_ == 1) Then
rni = psb_geamax(r,desc_a,info)
xni = psb_geamax(x,desc_a,info)
Else If (istop_ == 2) Then
rni = psb_genrm2(r,desc_a,info)
Endif
if (info /= 0) Then
info=4011
call psb_errpush(info,name)
goto 9999
End If
If (itx == 0) Then
rn0 = rni
End If
If (rn0 == 0.d0 ) Then
If (itrace_ > 0 ) Then
If (me == 0) Write(*,*) 'BiCGSTAB: ',itx,rn0
Endif
Exit restart
End If
If (istop_ == 1) Then
xni = psb_geamax(x,desc_a,info)
rerr = rni/(ani*xni+bni)
Else If (istop_ == 2) Then
rerr = rni/bn2
Endif
if (info /= 0) Then
info=4011
call psb_errpush(info,name)
goto 9999
End If
If (rerr<=eps) Then
Exit restart
End If
If (itrace_ > 0) then
if (((itx==0).or.(mod(itx,itrace_)==0)).and.(me == 0)) &
& write(*,'(a,i4,3(2x,es10.4))') 'bicgstab: ',itx,rerr
Endif
iteration: Do
it = it + 1
itx = itx + 1
If (debug) Write(*,*) 'Iteration: ',itx
rho_old = rho
rho = psb_gedot(q,r,desc_a,info)
!!$ write(0,'(i2," rho old ",2(f,2x))')me,rho,rho_old
If (debug) Write(0,*) 'Bi-CGSTAB RHO:',rho
If (rho==dzero) Then
If (debug) Write(0,*) 'Bi-CGSTAB Itxation breakdown R',rho
Exit iteration
Endif
If (it==1) Then
Call psb_geaxpby(done,r,dzero,p,desc_a,info)
Else
beta = (rho/rho_old)*(alpha/omega)
Call psb_geaxpby(-omega,v,done,p,desc_a,info)
Call psb_geaxpby(done,r,beta,p,desc_a,info)
End If
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( ifctb, 0, "st PREC" )
#endif
Call psb_precaply(prec,p,f,desc_a,info,work=aux)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( ifcte, 0, "ed PREC" )
imerr = MPE_Log_event( immb, 0, "st SPMM" )
#endif
Call psb_spmm(done,a,f,dzero,v,desc_a,info,&
& work=aux)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( imme, 0, "ed SPMM" )
#endif
sigma = psb_gedot(q,v,desc_a,info)
If (sigma==dzero) Then
If (debug) Write(0,*) 'Bi-CGSTAB Iteration breakdown S1', sigma
Exit iteration
Endif
If (debug) Write(0,*) 'Bi-CGSTAB SIGMA:',sigma
alpha = rho/sigma
Call psb_geaxpby(done,r,dzero,s,desc_a,info)
if(info.ne.0) then
call psb_errpush(4010,name,a_err='psb_geaxpby')
goto 9999
end if
Call psb_geaxpby(-alpha,v,done,s,desc_a,info)
if(info.ne.0) then
call psb_errpush(4010,name,a_err='psb_geaxpby')
goto 9999
end if
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( ifctb, 0, "st PREC" )
#endif
Call psb_precaply(prec,s,z,desc_a,info,work=aux)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( ifcte, 0, "ed PREC" )
#endif
if(info.ne.0) then
call psb_errpush(4010,name,a_err='psb_precaply')
goto 9999
end if
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( immb, 0, "st SPMM" )
#endif
Call psb_spmm(done,a,z,dzero,t,desc_a,info,&
& work=aux)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( imme, 0, "ed SPMM" )
#endif
if(info.ne.0) then
call psb_errpush(4010,name,a_err='psb_spmm')
goto 9999
end if
sigma = psb_gedot(t,t,desc_a,info)
If (sigma==dzero) Then
If (debug) Write(0,*) 'BI-CGSTAB ITERATION BREAKDOWN S2', sigma
Exit iteration
Endif
tau = psb_gedot(t,s,desc_a,info)
omega = tau/sigma
If (debug) Write(0,*) 'Bi-CGSTAB OMEGA:',omega
If (omega==dzero) Then
If (debug) Write(0,*) 'BI-CGSTAB ITERATION BREAKDOWN O',omega
Exit iteration
Endif
Call psb_geaxpby(alpha,f,done,x,desc_a,info)
Call psb_geaxpby(omega,z,done,x,desc_a,info)
Call psb_geaxpby(done,s,dzero,r,desc_a,info)
Call psb_geaxpby(-omega,t,done,r,desc_a,info)
If (istop_ == 1) Then
rni = psb_geamax(r,desc_a,info)
xni = psb_geamax(x,desc_a,info)
rerr = rni/(ani*xni+bni)
Else If (istop_ == 2) Then
rni = psb_genrm2(r,desc_a,info)
rerr = rni/bn2
Endif
If (rerr<=eps) Then
Exit restart
End If
If (itx.Ge.litmax) Exit restart
If (itrace_ > 0) then
if ((mod(itx,itrace_)==0).and.(me == 0)) &
& write(*,'(a,i4,3(2x,es10.4))') &
& 'bicgstab: ',itx,rerr
Endif
End Do iteration
End Do restart
If (itrace_ > 0) then
if (me == 0) write(*,'(a,i4,3(2x,es10.4))') 'bicgstab: ',itx,rerr
Endif
If (Present(err)) err=rerr
If (Present(iter)) iter = itx
If (rerr>eps) Then
Write(0,*) 'BI-CGSTAB failed to converge to ',EPS,&
& ' in ',ITX,' iterations. '
End If
Deallocate(aux)
Call psb_gefree(wwrk,desc_a,info)
! restore external global coherence behaviour
call psb_restore_coher(ictxt,isvch)
#ifdef MPE_KRYLOV
imerr = MPE_Log_event( istpe, 0, "ed CGSTAB" )
#endif
if(info/=0) then
call psb_errpush(info,name)
goto 9999
end if
call psb_erractionrestore(err_act)
return
9999 continue
call psb_erractionrestore(err_act)
if (err_act.eq.psb_act_abort_) then
call psb_error(ictxt)
return
end if
return
End Subroutine psb_dcgstab