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473 lines
15 KiB
Fortran
473 lines
15 KiB
Fortran
!!$
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!!$ Parallel Sparse BLAS v2.0
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!!$ (C) Copyright 2006 Salvatore Filippone University of Rome Tor Vergata
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!!$ Alfredo Buttari University of Rome Tor Vergata
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!!$
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!!$ Contributions to this routine:
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!!$ Daniela di Serafino Second University of Naples
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!!$ Pasqua D'Ambra ICAR-CNR
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!!$
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!!$ Redistribution and use in source and binary forms, with or without
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!!$ modification, are permitted provided that the following conditions
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!!$ are met:
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!!$ 1. Redistributions of source code must retain the above copyright
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!!$ notice, this list of conditions and the following disclaimer.
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!!$ 2. Redistributions in binary form must reproduce the above copyright
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!!$ notice, this list of conditions, and the following disclaimer in the
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!!$ documentation and/or other materials provided with the distribution.
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!!$ 3. The name of the PSBLAS group or the names of its contributors may
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!!$ not be used to endorse or promote products derived from this
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!!$ software without specific written permission.
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!!$
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!!$ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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!!$ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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!!$ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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!!$ PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
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!!$ BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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!!$ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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!!$ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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!!$ INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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!!$ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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!!$ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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!!$ POSSIBILITY OF SUCH DAMAGE.
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!!$
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!!$
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!!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
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!!$ C C
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!!$ C References: C
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!!$ C [1] Duff, I., Marrone, M., Radicati, G., and Vittoli, C. C
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!!$ C Level 3 basic linear algebra subprograms for sparse C
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!!$ C matrices: a user level interface C
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!!$ C ACM Trans. Math. Softw., 23(3), 379-401, 1997. C
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!!$ C C
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!!$ C C
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!!$ C [2] S. Filippone, M. Colajanni C
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!!$ C PSBLAS: A library for parallel linear algebra C
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!!$ C computation on sparse matrices C
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!!$ C ACM Trans. on Math. Softw., 26(4), 527-550, Dec. 2000. C
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!!$ C C
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!!$ C [3] M. Arioli, I. Duff, M. Ruiz C
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!!$ C Stopping criteria for iterative solvers C
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!!$ C SIAM J. Matrix Anal. Appl., Vol. 13, pp. 138-144, 1992 C
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!!$ C C
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!!$ C C
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!!$ C [4] R. Barrett et al C
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!!$ C Templates for the solution of linear systems C
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!!$ C SIAM, 1993 C
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!!$ C C
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!!$ C C
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!!$ C [5] G. Sleijpen, D. Fokkema C
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!!$ C BICGSTAB(L) for linear equations involving unsymmetric C
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!!$ C matrices with complex spectrum C
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!!$ C Electronic Trans. on Numer. Analysis, Vol. 1, pp. 11-32, C
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!!$ C Sep. 1993 C
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!!$ C C
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!!$ C C
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!!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
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! File: psb_dgmresr.f90
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!
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! Subroutine: psb_dgmres
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! This subroutine implements the restarted GMRES method with right
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! preconditioning.
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!
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! Parameters:
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! a - type(<psb_dspmat_type>). The sparse matrix containing A.
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! prec - type(<psb_prec_type>). The data structure containing the preconditioner.
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! b - real,dimension(:). The right hand side.
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! x - real,dimension(:). The vector of unknowns.
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! eps - real. The error tolerance.
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! desc_a - type(<psb_desc_type>). The communication descriptor.
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! info - integer. Eventually returns an error code.
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! itmax - integer(optional). The maximum number of iterations.
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! iter - integer(optional). The number of iterations performed.
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! err - real(optional). The error on return.
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! itrace - integer(optional). The unit to write messages onto.
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! irst - integer(optional). The restart value.
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! istop - integer(optional). The stopping criterium.
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!
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Subroutine psb_dgmresr(a,prec,b,x,eps,desc_a,info,&
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&itmax,iter,err,itrace,irst,istop)
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use psb_base_mod
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use psb_prec_mod
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implicit none
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!!$ Parameters
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Type(psb_dspmat_type), Intent(in) :: a
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Type(psb_dprec_type), Intent(in) :: prec
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Type(psb_desc_type), Intent(in) :: desc_a
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Real(Kind(1.d0)), Intent(in) :: b(:)
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Real(Kind(1.d0)), Intent(inout) :: x(:)
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Real(Kind(1.d0)), Intent(in) :: eps
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integer, intent(out) :: info
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Integer, Optional, Intent(in) :: itmax, itrace, irst,istop
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Integer, Optional, Intent(out) :: iter
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Real(Kind(1.d0)), Optional, Intent(out) :: err
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!!$ local data
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Real(Kind(1.d0)), allocatable, target :: aux(:),w(:),w1(:), v(:,:)
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Real(Kind(1.d0)), allocatable :: c(:),s(:), h(:,:), rs(:),rst(:),xt(:)
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Real(Kind(1.d0)) :: rerr, scal, gm, rti, rti1
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Integer ::litmax, liter, naux, m, mglob, it,k, itrace_,&
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& np,me, n_row, n_col, nl, int_err(5)
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Logical, Parameter :: exchange=.True., noexchange=.False., use_drot=.true.
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Integer, Parameter :: irmax = 8
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Integer :: itx, i, isvch, ich, ictxt,istop_, err_act
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Logical, Parameter :: debug = .false.
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Real(Kind(1.d0)) :: rni, xni, bni, ani,bn2, dt
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real(kind(1.d0)), external :: dnrm2
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character(len=20) :: name
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info = 0
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name = 'psb_dgmres'
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call psb_erractionsave(err_act)
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If (debug) Write(0,*) 'entering psb_dgmres'
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ictxt = psb_cd_get_context(desc_a)
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Call psb_info(ictxt, me, np)
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If (debug) Write(0,*) 'psb_dgmres: from gridinfo',np,me
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mglob = psb_cd_get_global_rows(desc_a)
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n_row = psb_cd_get_local_rows(desc_a)
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n_col = psb_cd_get_local_cols(desc_a)
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if (present(istop)) then
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istop_ = istop
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else
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istop_ = 1
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endif
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!
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! ISTOP_ = 1: Normwise backward error, infinity norm
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! ISTOP_ = 2: ||r||/||b||, 2-norm
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!
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if ((istop_ < 1 ).or.(istop_ > 2 ) ) then
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write(0,*) 'psb_dgmres: invalid istop',istop_
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info=5001
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int_err(1)=istop_
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err=info
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call psb_errpush(info,name,i_err=int_err)
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goto 9999
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endif
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If (Present(itmax)) Then
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litmax = itmax
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Else
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litmax = 1000
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Endif
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If (Present(itrace)) Then
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itrace_ = itrace
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Else
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itrace_ = 0
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End If
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If (Present(irst)) Then
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nl = irst
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If (debug) Write(0,*) 'present: irst: ',irst,nl
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Else
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nl = 10
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If (debug) Write(0,*) 'not present: irst: ',irst,nl
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Endif
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if (nl <=0 ) then
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write(0,*) 'psb_dgmres: invalid irst ',nl
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info=5001
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int_err(1)=nl
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err=info
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call psb_errpush(info,name,i_err=int_err)
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goto 9999
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endif
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call psb_chkvect(mglob,1,size(x,1),1,1,desc_a,info)
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if(info /= 0) then
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info=4010
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call psb_errpush(info,name,a_err='psb_chkvect on X')
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goto 9999
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end if
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call psb_chkvect(mglob,1,size(b,1),1,1,desc_a,info)
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if(info /= 0) then
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info=4010
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call psb_errpush(info,name,a_err='psb_chkvect on B')
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goto 9999
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end if
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naux=4*n_col
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Allocate(aux(naux),h(nl+1,nl+1),&
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&c(nl+1),s(nl+1),rs(nl+1), rst(nl+1),stat=info)
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if (info == 0) Call psb_geall(v,desc_a,info,n=nl+1)
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if (info == 0) Call psb_geall(w,desc_a,info)
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if (info == 0) Call psb_geall(w1,desc_a,info)
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if (info == 0) Call psb_geall(xt,desc_a,info)
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if (info == 0) Call psb_geasb(v,desc_a,info)
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if (info == 0) Call psb_geasb(w,desc_a,info)
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if (info == 0) Call psb_geasb(w1,desc_a,info)
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if (info == 0) Call psb_geasb(xt,desc_a,info)
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if (info.ne.0) Then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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End If
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if (debug) write(0,*) 'Size of V,W,W1 ',size(v),size(v,1),&
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&size(w),size(w,1),size(w1),size(w1,1), size(v(:,1))
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! Ensure global coherence for convergence checks.
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call psb_set_coher(ictxt,isvch)
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if (istop_ == 1) then
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ani = psb_spnrmi(a,desc_a,info)
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bni = psb_geamax(b,desc_a,info)
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else if (istop_ == 2) then
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bn2 = psb_genrm2(b,desc_a,info)
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endif
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if (info.ne.0) Then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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End If
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itx = 0
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restart: Do
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! compute r0 = b-ax0
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! check convergence
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! compute v1 = r0/||r0||_2
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If (debug) Write(0,*) 'restart: ',itx,it
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it = 0
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Call psb_geaxpby(done,b,dzero,v(:,1),desc_a,info)
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if (info.ne.0) Then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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End If
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Call psb_spmm(-done,a,x,done,v(:,1),desc_a,info,work=aux)
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if (info.ne.0) Then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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End If
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rs(1) = psb_genrm2(v(:,1),desc_a,info)
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rs(2:) = dzero
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if (info.ne.0) Then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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End If
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scal=done/rs(1) ! rs(1) MIGHT BE VERY SMALL - USE DSCAL TO DEAL WITH IT?
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If (debug) Write(0,*) 'on entry to amax: b: ',Size(b),rs(1),scal
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!
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! check convergence
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!
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if (istop_ == 1) then
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rni = psb_geamax(v(:,1),desc_a,info)
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xni = psb_geamax(x,desc_a,info)
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rerr = rni/(ani*xni+bni)
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else if (istop_ == 2) then
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rni = psb_genrm2(v(:,1),desc_a,info)
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rerr = rni/bn2
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endif
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if (info.ne.0) Then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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End If
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If (rerr<=eps) Then
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Exit restart
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End If
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If (itrace_ > 0) then
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if ((mod(itx,itrace_)==0).and.(me == 0))&
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& write(*,'(a,i4,3(2x,es10.4))') 'gmres(l): ',itx,rerr
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end If
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v(:,1) = v(:,1) * scal
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If (itx.Ge.litmax) Exit restart
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!
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! inner iterations
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!
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inner: Do i=1,nl
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itx = itx + 1
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call psb_precaply(prec,v(:,i),w1,desc_a,info)
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Call psb_spmm(done,a,w1,dzero,w,desc_a,info,work=aux)
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!
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do k = 1, i
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h(k,i) = psb_gedot(v(:,k),w,desc_a,info)
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call psb_geaxpby(-h(k,i),v(:,k),done,w,desc_a,info)
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end do
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h(i+1,i) = psb_genrm2(w,desc_a,info)
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scal=done/h(i+1,i)
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call psb_geaxpby(scal,w,dzero,v(:,i+1),desc_a,info)
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if (use_drot) then
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do k=2,i
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call drot(1,h(k-1,i),1,h(k,i),1,c(k-1),s(k-1))
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enddo
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rti = h(i,i)
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rti1 = h(i+1,i)
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call drotg(rti,rti1,c(i),s(i))
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call drot(1,h(i,i),1,h(i+1,i),1,c(i),s(i))
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h(i+1,i) = dzero
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call drot(1,rs(i),1,rs(i+1),1,c(i),s(i))
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else
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do k=2,i
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dt = h(k-1,i)
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h(k-1,i) = c(k-1)*dt + s(k-1)*h(k,i)
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h(k,i) = -s(k-1)*dt + c(k-1)*h(k,i)
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enddo
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gm = safe_dn2(h(i,i),h(i+1,i))
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if (debug) write(0,*) 'GM : ',gm
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gm = max(gm,epstol)
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c(i) = h(i,i)/gm
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s(i) = h(i+1,i)/gm
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rs(i+1) = -s(i)*rs(i)
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rs(i) = c(i)*rs(i)
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h(i,i) = c(i)*h(i,i)+s(i)*h(i+1,i)
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endif
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if (istop_ == 1) then
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!
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! build x and then compute the residual and its infinity norm
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!
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rst = rs
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xt = dzero
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call dtrsm('l','u','n','n',i,1,done,h,size(h,1),rst,size(rst,1))
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if (debug) write(0,*) 'Rebuild x-> RS:',rst(1:nl)
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do k=1, i
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call psb_geaxpby(rst(k),v(:,k),done,xt,desc_a,info)
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end do
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call psb_precaply(prec,xt,desc_a,info)
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call psb_geaxpby(done,x,done,xt,desc_a,info)
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call psb_geaxpby(done,b,dzero,w1,desc_a,info)
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call psb_spmm(-done,a,xt,done,w1,desc_a,info,work=aux)
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rni = psb_geamax(w1,desc_a,info)
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xni = psb_geamax(xt,desc_a,info)
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rerr = rni/(ani*xni+bni)
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!
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else if (istop_ == 2) then
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!
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! compute the residual 2-norm as byproduct of the solution
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! procedure of the least-squares problem
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!
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rni = abs(rs(i+1))
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rerr = rni/bn2
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endif
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if (rerr < eps ) then
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if (istop_ == 1) then
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x = xt
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else if (istop_ == 2) then
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!
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! build x
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!
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call dtrsm('l','u','n','n',i,1,done,h,size(h,1),rs,size(rs,1))
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if (debug) write(0,*) 'Rebuild x-> RS:',rs(21:nl)
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w1 = dzero
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do k=1, i
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call psb_geaxpby(rs(k),v(:,k),done,w1,desc_a,info)
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end do
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call psb_precaply(prec,w1,w,desc_a,info)
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call psb_geaxpby(done,w,done,x,desc_a,info)
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end if
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exit restart
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end if
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If (itrace_ > 0) then
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if ((mod(itx,itrace_)==0).and.(me == 0))&
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& write(*,'(a,i4,3(2x,es10.4))') 'gmres(l): ',itx,rerr
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end If
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end Do inner
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if (istop_ == 1) then
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x = xt
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else if (istop_ == 2) then
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!
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! build x
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!
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call dtrsm('l','u','n','n',nl,1,done,h,size(h,1),rs,size(rs,1))
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if (debug) write(0,*) 'Rebuild x-> RS:',rs(21:nl)
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w1 = dzero
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do k=1, nl
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call psb_geaxpby(rs(k),v(:,k),done,w1,desc_a,info)
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end do
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call psb_precaply(prec,w1,w,desc_a,info)
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call psb_geaxpby(done,w,done,x,desc_a,info)
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end if
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End Do restart
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If (itrace_ > 0) then
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if (me == 0) write(*,'(a,i4,3(2x,es10.4))') 'gmres(l): ',itx,rerr
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end If
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If (Present(err)) err=rerr
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If (Present(iter)) iter = itx
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If ((rerr>eps).and. (me == 0)) Then
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Write(0,*) 'gmresr(l) failed to converge to ',eps,&
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& ' in ',itx,' iterations '
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End If
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Deallocate(aux,h,c,s,rs,rst, stat=info)
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Call psb_gefree(v,desc_a,info)
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Call psb_gefree(w,desc_a,info)
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Call psb_gefree(w1,desc_a,info)
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Call psb_gefree(xt,desc_a,info)
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! restore external global coherence behaviour
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call psb_restore_coher(ictxt,isvch)
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if (info /= 0) then
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info=4011
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call psb_errpush(info,name)
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goto 9999
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end if
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call psb_erractionrestore(err_act)
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return
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9999 continue
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call psb_erractionrestore(err_act)
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if (err_act.eq.psb_act_abort_) then
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call psb_error()
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return
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end if
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return
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contains
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function safe_dn2(a,b)
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real(kind(1.d0)), intent(in) :: a, b
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real(kind(1.d0)) :: safe_dn2
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real(kind(1.d0)) :: t
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t = max(abs(a),abs(b))
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if (t==0.d0) then
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safe_dn2 = 0.d0
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else
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safe_dn2 = t * sqrt(abs(a/t)**2 + abs(b/t)**2)
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endif
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return
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end function safe_dn2
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End Subroutine psb_dgmresr
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