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334 lines
12 KiB
Fortran
334 lines
12 KiB
Fortran
!
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! Parallel Sparse BLAS version 3.5
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! (C) Copyright 2006-2018
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! Salvatore Filippone
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! Alfredo Buttari
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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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! File: psb_scg.f90
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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
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! C C
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! C C
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! CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
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! File: psb_scg.f90
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!
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! Subroutine: psb_scg
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! This subroutine implements the Conjugate Gradient method.
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!
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!
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! Arguments:
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!
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! a - type(psb_sspmat_type) Input: sparse matrix containing A.
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! prec - class(psb_sprec_type) Input: preconditioner
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! b(:) - real Input: vector containing the
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! right hand side B
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! x(:) - real 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|/(|a||x|+|b|); here the iteration is
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! stopped when |r| <= eps * (|a||x|+|b|)
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! 2: err = |r|/|b|; here the iteration is
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! stopped when |r| <= eps * |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_scg_vect(a,prec,b,x,eps,desc_a,info,&
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& itmax,iter,err,itrace,istop,cond)
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use psb_base_mod
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use psb_prec_mod
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use psb_s_krylov_conv_mod
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use psb_krylov_mod
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implicit none
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type(psb_sspmat_type), intent(in) :: a
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Type(psb_desc_type), Intent(in) :: desc_a
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class(psb_sprec_type), intent(inout) :: prec
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type(psb_s_vect_type), Intent(inout) :: b
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type(psb_s_vect_type), Intent(inout) :: x
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Real(psb_spk_), Intent(in) :: eps
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integer(psb_ipk_), intent(out) :: info
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integer(psb_ipk_), Optional, Intent(in) :: itmax, itrace, istop
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integer(psb_ipk_), Optional, Intent(out) :: iter
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Real(psb_spk_), Optional, Intent(out) :: err,cond
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! = Local data
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real(psb_spk_), allocatable, target :: aux(:),td(:),tu(:),eig(:),ewrk(:)
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integer(psb_mpk_), allocatable :: ibl(:), ispl(:), iwrk(:)
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type(psb_s_vect_type), allocatable, target :: wwrk(:)
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type(psb_s_vect_type), pointer :: q, p, r, z, w
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real(psb_spk_) :: alpha, beta, rho, rho_old, sigma,alpha_old,beta_old
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integer(psb_ipk_) :: itmax_, istop_, naux, it, itx, itrace_,&
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& n_col, n_row,err_act, ieg,nspl, istebz
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integer(psb_lpk_) :: mglob
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integer(psb_ipk_) :: debug_level, debug_unit
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integer(psb_ipk_) :: np, me, ictxt
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real(psb_dpk_) :: derr
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type(psb_itconv_type) :: stopdat
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logical :: do_cond
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character(len=20) :: name
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character(len=*), parameter :: methdname='CG'
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info = psb_success_
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name = 'psb_scg'
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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 = desc_a%get_context()
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call psb_info(ictxt, me, np)
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if (.not.allocated(b%v)) then
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info = psb_err_invalid_vect_state_
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call psb_errpush(info,name)
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goto 9999
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endif
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if (.not.allocated(x%v)) then
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info = psb_err_invalid_vect_state_
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call psb_errpush(info,name)
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goto 9999
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endif
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mglob = desc_a%get_global_rows()
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n_row = desc_a%get_local_rows()
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n_col = desc_a%get_local_cols()
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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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call psb_chkvect(mglob,lone,x%get_nrows(),lone,lone,desc_a,info)
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if (info == psb_success_)&
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& call psb_chkvect(mglob,lone,b%get_nrows(),lone,lone,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/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=5_psb_ipk_)
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if (info == psb_success_) call psb_geasb(wwrk,desc_a,info,mold=x%v,scratch=.true.)
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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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p => wwrk(1)
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q => wwrk(2)
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r => wwrk(3)
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z => wwrk(4)
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w => wwrk(5)
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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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do_cond=present(cond)
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if (do_cond) then
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istebz = 0
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allocate(td(itmax_),tu(itmax_), eig(itmax_),&
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& ibl(itmax_),ispl(itmax_),iwrk(3*itmax_),ewrk(4*itmax_),&
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& stat=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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end if
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itx=0
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alpha = szero
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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 (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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call psb_init_conv(methdname,istop_,itrace_,itmax_,a,x,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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iteration: do
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it = it + 1
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itx = itx + 1
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call prec%apply(r,z,desc_a,info,work=aux)
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rho_old = rho
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rho = psb_gedot(r,z,desc_a,info)
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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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else
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if (rho_old == 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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& ': CG Iteration breakdown rho'
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exit iteration
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endif
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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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end if
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call psb_spmm(sone,a,p,szero,q,desc_a,info,work=aux)
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sigma = psb_gedot(p,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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& ': CG Iteration breakdown sigma'
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exit iteration
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endif
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alpha_old = alpha
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alpha = rho/sigma
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if (do_cond) then
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istebz = istebz + 1
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if (istebz == 1) then
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td(istebz) = sone/alpha
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else
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td(istebz) = sone/alpha + beta/alpha_old
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tu(istebz-1) = sqrt(beta)/alpha_old
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end if
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end if
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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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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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if (do_cond) then
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if (me == psb_root_) then
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#if defined(HAVE_LAPACK)
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call sstebz('A','E',istebz,szero,szero,0,0,-sone,td,tu,&
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& ieg,nspl,eig,ibl,ispl,ewrk,iwrk,info)
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if (info < 0) then
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call psb_errpush(psb_err_from_subroutine_ai_,name,&
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& a_err='sstebz',i_err=(/info/))
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info=psb_err_from_subroutine_ai_
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goto 9999
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end if
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cond = eig(ieg)/eig(1)
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#else
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cond = szero
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#endif
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info=psb_success_
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end if
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call psb_bcast(ictxt,cond)
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end if
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call psb_end_conv(methdname,itx,desc_a,stopdat,info,derr,iter)
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if (present(err)) err = derr
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if (info == psb_success_) call psb_gefree(wwrk,desc_a,info)
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if (info == psb_success_) deallocate(aux,stat=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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call psb_erractionrestore(err_act)
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return
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9999 call psb_error_handler(err_act)
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return
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end subroutine psb_scg_vect
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