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psblas3/krylov/psb_dcgs.f90

351 lines
11 KiB
Fortran

!!$
!!$ 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_dcgs.f90
!
! Subroutine: psb_dcgs
!
! 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_dcgs(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_desc_type), Intent(in) :: desc_a
Type(psb_dprec_type), Intent(in) :: prec
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 :: ww(:), q(:),&
& r(:), p(:), v(:), s(:), z(:), f(:), rt(:),qt(:),uv(:)
Real(Kind(1.d0)) :: rerr
Integer :: litmax, naux, m, mglob, it, itrace_,int_err(5),&
& np,me, n_row, n_col,istop_, err_act
Character ::diagl, diagu
Logical, Parameter :: exchange=.True., noexchange=.False.
Integer, Parameter :: irmax = 8
Integer :: itx, i, isvch, ich, ictxt
Logical, Parameter :: debug = .false.
Real(Kind(1.d0)) :: alpha, beta, rho, rho_old, rni, xni, bni, ani,bn2,&
& sigma
character(len=20) :: name,ch_err
info = 0
name = 'psb_dcgs'
call psb_erractionsave(err_act)
If (debug) Write(*,*) 'entering psb_dcgs'
ictxt = psb_cd_get_context(desc_a)
Call psb_info(ictxt, me, np)
If (debug) Write(*,*) 'psb_dcgs: from gridinfo',np,me
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
!
!!$
!!$ If ((prec%prec < 0).Or.(prec%prec > 6) ) Then
!!$ Write(0,*) 'f90_cgstab: invalid iprec',prec%prec
!!$ If (Present(ierr)) ierr=-1
!!$ Return
!!$ Endif
if ((istop_ < 1 ).or.(istop_ > 2 ) ) then
write(0,*) 'psb_cgs: invalid istop',istop_
info=5001
int_err=istop_
err=info
call psb_errpush(info,name,i_err=int_err)
goto 9999
endif
naux=4*n_col
Allocate(aux(naux),stat=info)
if (info == 0) Call psb_geall(wwrk,desc_a,info,n=11)
if (info == 0) Call psb_geasb(wwrk,desc_a,info)
if (info.ne.0) Then
info=4011
call psb_errpush(info,name)
goto 9999
End If
q => wwrk(:,1)
qt => wwrk(:,2)
r => wwrk(:,3)
rt => wwrk(:,4)
p => wwrk(:,5)
v => wwrk(:,6)
uv => wwrk(:,7)
z => wwrk(:,8)
f => wwrk(:,9)
s => wwrk(:,10)
ww => wwrk(:,11)
If (Present(itmax)) Then
litmax = itmax
Else
litmax = 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)
diagl = 'u'
diagu = 'u'
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.Ge.litmax) Exit restart
it = 0
Call psb_geaxpby(done,b,dzero,r,desc_a,info)
Call psb_spmm(-done,a,x,done,r,desc_a,info,work=aux)
Call psb_geaxpby(done,r,dzero,rt,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)
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(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 ((mod(itx,itrace_)==0).and.(me == 0))&
& write(*,'(a,i4,3(2x,es10.4))') 'cgs: ',itx,rerr
end If
iteration: Do
it = it + 1
itx = itx + 1
If (debug) Write(*,*) 'iteration: ',itx
rho_old = rho
rho = psb_gedot(rt,r,desc_a,info)
If (rho==dzero) Then
If (debug) Write(0,*) 'cgs iteration breakdown r',rho
Exit iteration
Endif
If (it==1) Then
Call psb_geaxpby(done,r,dzero,uv,desc_a,info)
Call psb_geaxpby(done,r,dzero,p,desc_a,info)
Else
beta = (rho/rho_old)
Call psb_geaxpby(done,r,dzero,uv,desc_a,info)
Call psb_geaxpby(beta,q,done,uv,desc_a,info)
Call psb_geaxpby(done,q,beta,p,desc_a,info)
Call psb_geaxpby(done,uv,beta,p,desc_a,info)
End If
Call psb_precaply(prec,p,f,desc_a,info,work=aux)
Call psb_spmm(done,a,f,dzero,v,desc_a,info,&
& work=aux)
sigma = psb_gedot(rt,v,desc_a,info)
If (sigma==dzero) Then
If (debug) Write(0,*) 'cgs iteration breakdown s1', sigma
Exit iteration
Endif
alpha = rho/sigma
Call psb_geaxpby(done,uv,dzero,q,desc_a,info)
Call psb_geaxpby(-alpha,v,done,q,desc_a,info)
Call psb_geaxpby(done,uv,dzero,s,desc_a,info)
Call psb_geaxpby(done,q,done,s,desc_a,info)
Call psb_precaply(prec,s,z,desc_a,info,work=aux)
Call psb_geaxpby(alpha,z,done,x,desc_a,info)
Call psb_spmm(done,a,z,dzero,qt,desc_a,info,&
& work=aux)
Call psb_geaxpby(-alpha,qt,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))') 'cgs: ',itx,rerr
end If
End Do iteration
End Do restart
If (itrace_ > 0) then
if ((mod(itx,itrace_)==0).and.(me == 0))&
& write(*,'(a,i4,3(2x,es10.4))') 'cgs: ',itx,rerr
end If
If (Present(err)) err=rerr
If (Present(iter)) iter = itx
If (rerr>eps) Then
Write(0,*) 'cgs 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)
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()
return
end if
return
End Subroutine psb_dcgs