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339 lines
12 KiB
Fortran
339 lines
12 KiB
Fortran
!!$
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!!$ Parallel Sparse BLAS version 2.2
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!!$ (C) Copyright 2006/2007/2008
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!!$ 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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!!$ 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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!!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
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!
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! File: psb_sbicg.f90
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!
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! Subroutine: psb_sbicg
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! This subroutine implements the BiCG method.
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!
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! Arguments:
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!
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! a - type(psb_s_sparse_mat) Input: sparse matrix containing A.
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! prec - class(psb_sprec_type) Input: preconditioner
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! b - real,dimension(:) Input: vector containing the
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! right hand side B
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! x - real,dimension(:) Input/Output: vector containing the
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! initial guess and final solution X.
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! eps - real Input: Stopping tolerance; the iteration is
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! stopped when the error estimate |err| <= eps
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! desc_a - type(psb_desc_type). Input: The communication descriptor.
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! info - integer. Output: Return code
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!
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! itmax - integer(optional) Input: maximum number of iterations to be
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! performed.
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! iter - integer(optional) Output: how many iterations have been
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! performed.
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! performed.
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! err - real (optional) Output: error estimate on exit. If the
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! denominator of the estimate is exactly
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! 0, it is changed into 1.
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! itrace - integer(optional) Input: print an informational message
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! with the error estimate every itrace
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! iterations
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! istop - integer(optional) Input: stopping criterion, or how
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! to estimate the error.
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! 1: err = |r|/|b|; here the iteration is
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! stopped when |r| <= eps * |b|
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! 2: err = |r|/(|a||x|+|b|); here the iteration is
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! stopped when |r| <= eps * (|a||x|+|b|)
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! where r is the (preconditioned, recursive
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! estimate of) residual.
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!
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!
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subroutine psb_sbicg(a,prec,b,x,eps,desc_a,info,itmax,iter,err,itrace,istop)
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use psb_sparse_mod
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use psb_prec_mod
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use psb_inner_krylov_mod
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use psb_krylov_mod
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implicit none
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!!$ parameters
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type(psb_s_sparse_mat), intent(in) :: a
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class(psb_sprec_type), intent(in) :: prec
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type(psb_desc_type), intent(in) :: desc_a
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real(psb_spk_), intent(in) :: b(:)
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real(psb_spk_), intent(inout) :: x(:)
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real(psb_spk_), intent(in) :: eps
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integer, intent(out) :: info
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integer, optional, intent(in) :: itmax, itrace, istop
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integer, optional, intent(out) :: iter
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real(psb_spk_), optional, intent(out) :: err
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!!$ local data
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real(psb_spk_), allocatable, target :: aux(:),wwrk(:,:)
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real(psb_spk_), pointer :: ww(:), q(:),&
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& r(:), p(:), zt(:), pt(:), z(:), rt(:),qt(:)
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integer :: int_err(5)
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integer ::itmax_, naux, mglob, it, itrace_,&
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& np,me, n_row, n_col, istop_, err_act
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integer :: debug_level, debug_unit
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logical, parameter :: exchange=.true., noexchange=.false.
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integer, parameter :: irmax = 8
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integer :: itx, isvch, ictxt
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real(psb_spk_) :: alpha, beta, rho, rho_old, sigma
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type(psb_itconv_type) :: stopdat
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real(psb_dpk_) :: derr
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character(len=20) :: name,ch_err
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character(len=*), parameter :: methdname='BiCG'
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info = psb_success_
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name = 'psb_sbicg'
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call psb_erractionsave(err_act)
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debug_unit = psb_get_debug_unit()
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debug_level = psb_get_debug_level()
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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_level >= psb_debug_ext_)&
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& write(debug_unit,*) me,' ',trim(name),': from psb_info',np
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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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! Ensure global coherence for convergence checks.
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call psb_set_coher(ictxt,isvch)
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if (present(istop)) then
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istop_ = istop
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else
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istop_ = 2
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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|| norm 2
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!
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if ((istop_ < 1 ).or.(istop_ > 2 ) ) then
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info=psb_err_invalid_istop_
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int_err=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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call psb_chkvect(mglob,1,size(x,1),1,1,desc_a,info)
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if(info /= psb_success_) then
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info=psb_err_from_subroutine_
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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 /= psb_success_) then
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info=psb_err_from_subroutine_
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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),stat=info)
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if (info == psb_success_) call psb_geall(wwrk,desc_a,info,n=9)
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if (info == psb_success_) call psb_geasb(wwrk,desc_a,info)
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if(info /= psb_success_) then
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info=psb_err_from_subroutine_non_
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ch_err='psb_asb'
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err=info
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call psb_errpush(info,name,a_err=ch_err)
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goto 9999
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end if
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q => wwrk(:,1)
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qt => wwrk(:,2)
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r => wwrk(:,3)
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rt => wwrk(:,4)
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p => wwrk(:,5)
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pt => wwrk(:,6)
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z => wwrk(:,7)
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zt => wwrk(:,8)
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ww => wwrk(:,9)
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if (present(itmax)) then
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itmax_ = itmax
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else
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itmax_ = 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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itx = 0
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call psb_init_conv(methdname,istop_,itrace_,itmax_,a,b,eps,desc_a,stopdat,info)
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if (info /= psb_success_) Then
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call psb_errpush(psb_err_from_subroutine_non_,name)
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goto 9999
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End If
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restart: do
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!!$
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!!$ r0 = b-ax0
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!!$
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if (itx >= itmax_) exit restart
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it = 0
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call psb_geaxpby(sone,b,szero,r,desc_a,info)
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if (info == psb_success_) call psb_spmm(-sone,a,x,sone,r,desc_a,info,work=aux)
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if (debug_level >= psb_debug_ext_)&
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& write(debug_unit,*) me,' ',trim(name),' Done spmm',info
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if (info == psb_success_) call psb_geaxpby(sone,r,szero,rt,desc_a,info)
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if(info /= psb_success_) then
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info=psb_err_from_subroutine_non_
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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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rho = szero
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! Perhaps we already satisfy the convergence criterion...
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if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart
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if (info /= psb_success_) Then
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call psb_errpush(psb_err_from_subroutine_non_,name)
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goto 9999
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End If
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iteration: do
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it = it + 1
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itx = itx + 1
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if (debug_level >= psb_debug_ext_) &
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& write(debug_unit,*) me,' ',trim(name),'iteration: ',itx
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call prec%apply(r,z,desc_a,info,work=aux)
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if (info == psb_success_) call prec%apply(rt,zt,desc_a,info,trans='t',work=aux)
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rho_old = rho
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rho = psb_gedot(rt,z,desc_a,info)
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if (rho == szero) then
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if (debug_level >= psb_debug_ext_) &
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& write(debug_unit,*) me,' ',trim(name),&
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& ' iteration breakdown r',rho
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exit iteration
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endif
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if (it == 1) then
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call psb_geaxpby(sone,z,szero,p,desc_a,info)
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call psb_geaxpby(sone,zt,szero,pt,desc_a,info)
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else
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beta = (rho/rho_old)
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call psb_geaxpby(sone,z,beta,p,desc_a,info)
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call psb_geaxpby(sone,zt,beta,pt,desc_a,info)
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end if
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call psb_spmm(sone,a,p,szero,q,desc_a,info,&
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& work=aux)
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call psb_spmm(sone,a,pt,szero,qt,desc_a,info,&
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& work=aux,trans='t')
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sigma = psb_gedot(pt,q,desc_a,info)
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if (sigma == szero) then
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if (debug_level >= psb_debug_ext_) &
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& write(debug_unit,*) me,' ',trim(name),&
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& ' iteration breakdown s1', sigma
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exit iteration
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endif
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alpha = rho/sigma
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call psb_geaxpby(alpha,p,sone,x,desc_a,info)
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call psb_geaxpby(-alpha,q,sone,r,desc_a,info)
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call psb_geaxpby(-alpha,qt,sone,rt,desc_a,info)
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if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart
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if (info /= psb_success_) Then
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call psb_errpush(psb_err_from_subroutine_non_,name)
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goto 9999
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End If
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end do iteration
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end do restart
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call psb_end_conv(methdname,itx,desc_a,stopdat,info,derr,iter)
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if (present(err)) then
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err = derr
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end if
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deallocate(aux, stat=info)
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if (info == psb_success_) call psb_gefree(wwrk,desc_a,info)
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if (info /= psb_success_) then
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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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! restore external global coherence behaviour
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call psb_restore_coher(ictxt,isvch)
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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 == 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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end subroutine psb_sbicg
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