!!$ !!$ Parallel Sparse BLAS version 3.4 !!$ (C) Copyright 2006, 2010, 2015 !!$ Salvatore Filippone University of Rome Tor Vergata !!$ Alfredo Buttari CNRS-IRIT, Toulouse !!$ !!$ 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. !!$ !!$ ! File: psb_sfcg.f90 !! !! Contributors: Ambra Abdullahi (UNITOV) and Pasqua D’Ambra (IAC-CNR) !! !!$ 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 [4] Notay, Yvan C !!$ C Flexible Conjugate gradients C !!$ C SIAM Journal on Scientific Computing 22(4), C !!$ C pp. 1444-1460, 2000 C !!$ C C !!$ C C !!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC ! File: psb_sfcg.f90 ! ! Subroutine: psb_sfcg ! This subroutine implements the Flexible Conjugate Gradient method. ! ! ! Arguments: ! ! a - type(psb_sspmat_type) Input: sparse matrix containing A. ! prec - class(psb_sprec_type) Input: preconditioner ! b(:) - real Input: vector containing the ! right hand side B ! x(:) - real Input/Output: vector containing the ! initial guess and final solution X. ! eps - real Input: Stopping tolerance; the iteration is ! stopped when the error estimate |err| <= eps ! desc_a - type(psb_desc_type). Input: The communication descriptor. ! info - integer. Output: Return code ! ! itmax - integer(optional) Input: maximum number of iterations to be ! performed. ! iter - integer(optional) Output: how many iterations have been ! performed. ! performed. ! err - real (optional) Output: error estimate on exit. If the ! denominator of the estimate is exactly ! 0, it is changed into 1. ! itrace - integer(optional) Input: print an informational message ! with the error estimate every itrace ! iterations ! istop - integer(optional) Input: stopping criterion, or how ! to estimate the error. ! 1: err = |r|/(|a||x|+|b|); here the iteration is ! stopped when |r| <= eps * (|a||x|+|b|) ! 2: err = |r|/|b|; here the iteration is ! stopped when |r| <= eps * |b| ! where r is the (preconditioned, recursive ! estimate of) residual. ! ! subroutine psb_sfcg_vect(a,prec,b,x,eps,desc_a,info,& & itmax,iter,err,itrace,istop,cond) use psb_base_mod use psb_prec_mod use psb_s_krylov_conv_mod use psb_krylov_mod implicit none type(psb_sspmat_type), intent(in) :: a Type(psb_desc_type), Intent(in) :: desc_a class(psb_sprec_type), intent(inout) :: prec type(psb_s_vect_type), Intent(inout) :: b type(psb_s_vect_type), Intent(inout) :: x real(psb_spk_), Intent(in) :: eps integer(psb_ipk_), intent(out) :: info integer(psb_ipk_), Optional, Intent(in) :: itmax, itrace, istop integer(psb_ipk_), Optional, Intent(out) :: iter real(psb_spk_), Optional, Intent(out) :: err,cond ! = Local data type(psb_s_vect_type) :: v, w type(psb_s_vect_type), dimension(0:1) :: d real(psb_spk_) :: alpha, tau, tau1, beta, delta real(psb_dpk_) :: derr integer(psb_ipk_) :: i, idx, nc2l, it, itx, istop_, itmax_, itrace_ integer(psb_ipk_) :: n_col, mglob, naux, err_act integer(psb_ipk_) :: debug_level, debug_unit integer(psb_ipk_) :: np, me, ictxt real(psb_spk_), allocatable, target :: aux(:) character(len=20) :: name type(psb_itconv_type) :: stopdat character(len=*), parameter :: methdname='FCG' info = psb_success_ name = 'psb_sfcg' call psb_erractionsave(err_act) debug_unit = psb_get_debug_unit() debug_level = psb_get_debug_level() ictxt = desc_a%get_context() call psb_info(ictxt, me, np) if (.not.allocated(b%v)) then info = psb_err_invalid_vect_state_ call psb_errpush(info,name) goto 9999 endif if (.not.allocated(x%v)) then info = psb_err_invalid_vect_state_ call psb_errpush(info,name) goto 9999 endif mglob = desc_a%get_global_rows() n_col = desc_a%get_local_cols() if (present(istop)) then istop_ = istop else istop_ = 2 endif call psb_chkvect(mglob,ione,x%get_nrows(),ione,ione,desc_a,info) if (info == psb_success_)& & call psb_chkvect(mglob,ione,b%get_nrows(),ione,ione,desc_a,info) if(info /= psb_success_) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='psb_chkvect on X/B') goto 9999 end if naux=4*n_col allocate(aux(naux), stat=info) if (present(itmax)) then itmax_ = itmax else itmax_ = 1000 endif if (present(itrace)) then itrace_ = itrace else itrace_ = 0 end if !Assemble w, v call psb_geasb(w,& & desc_a,info,& & scratch=.true.,mold=b%v) call psb_geasb(v,& & desc_a,info,& & scratch=.true.,mold=b%v) !Assemble d(0) and d(1) call psb_geasb(d(0),& & desc_a,info,& & scratch=.true.,mold=x%v) call psb_geasb(d(1),& & desc_a,info,& & scratch=.true.,mold=x%v) call psb_init_conv(methdname,istop_,itrace_,itmax_,a,b,eps,desc_a,stopdat,info) itx=0 restart: do if (itx>= itmax_) exit restart ! w=b call psb_geaxpby(sone,b,szero,w,& & desc_a,info) if (psb_errstatus_fatal()) then nc2l = desc_a%get_local_cols() info=psb_err_alloc_request_ call psb_errpush(info,name,i_err=(/2*nc2l,izero,izero,izero,izero/),& & a_err='real(psb_spk_)') goto 9999 end if !Compute v = Ax call psb_spmm(sone,a,x,szero,v,desc_a,info) if (info /= psb_success_) then call psb_errpush(psb_err_internal_error_,name,& & a_err='Error during residue') goto 9999 end if !Compute w = -Ax + b call psb_geaxpby(-sone, v, sone, w, desc_a, info) !Apply the preconditioner idx=0 call prec%apply(w,d(idx),desc_a,info,work=aux) delta = psb_gedot(d(idx), w, desc_a, info) !Loop itx = 0 call psb_init_conv(methdname,istop_,itrace_,itmax_,a,b,eps,desc_a,stopdat,info) if (info /= psb_success_) Then call psb_errpush(psb_err_from_subroutine_non_,name) goto 9999 End If iteration: do call psb_spmm(sone,a,d(idx),szero,v,desc_a,info) if (info /= psb_success_) then call psb_errpush(psb_err_internal_error_,name,& & a_err='Error during residue') goto 9999 end if tau = psb_gedot(d(idx), v, desc_a, info) alpha = delta/tau !Update solution x call psb_geaxpby(alpha, d(idx), sone, x, desc_a, info) !Update residual w call psb_geaxpby(-alpha, v, sone, w, desc_a, info) itx = itx + 1 idx=mod(itx ,2) call d(idx)%set(szero) call prec%apply(w,d(idx),desc_a,info,work=aux) tau1= psb_gedot(d(idx), v, desc_a, info) beta=tau1/tau if (idx == 1) then call psb_geaxpby(-beta, d(idx - 1), sone, d(idx), desc_a, info) else call psb_geaxpby(-beta, d(idx + 1), sone, d(idx), desc_a, info) endif delta = psb_gedot(w, d(idx), desc_a, info) if (psb_check_conv(methdname,itx ,x,w,desc_a,stopdat,info)) exit restart if (info /= psb_success_) Then call psb_errpush(psb_err_from_subroutine_non_,name) goto 9999 End If end do iteration end do restart call psb_end_conv(methdname,itx ,desc_a,stopdat,info,derr,iter) if (present(err)) err = derr 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_sfcg_vect