! ! Parallel Sparse BLAS version 3.5 ! (C) Copyright 2006-2018 ! Salvatore Filippone ! Alfredo Buttari ! ! Redistribution and use in source and binary forms, with or without ! modification, are permitted provided that the following conditions ! are met: ! 1. Redistributions of source code must retain the above copyright ! notice, this list of conditions and the following disclaimer. ! 2. Redistributions in binary form must reproduce the above copyright ! notice, this list of conditions, and the following disclaimer in the ! documentation and/or other materials provided with the distribution. ! 3. The name of the PSBLAS group or the names of its contributors may ! not be used to endorse or promote products derived from this ! software without specific written permission. ! ! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ! ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ! TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR ! PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS ! BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR ! CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF ! SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS ! INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN ! CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ! ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ! POSSIBILITY OF SUCH DAMAGE. ! ! ! CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC ! C C ! C References: C ! C [1] Duff, I., Marrone, M., Radicati, G., and Vittoli, C. C ! C Level 3 basic linear algebra subprograms for sparse C ! C matrices: a user level interface C ! C ACM Trans. Math. Softw., 23(3), 379-401, 1997. C ! C C ! C C ! C [2] S. Filippone, M. Colajanni C ! C PSBLAS: A library for parallel linear algebra C ! C computation on sparse matrices C ! C ACM Trans. on Math. Softw., 26(4), 527-550, Dec. 2000. C ! C C ! C [3] M. Arioli, I. Duff, M. Ruiz C ! C Stopping criteria for iterative solvers C ! C SIAM J. Matrix Anal. Appl., Vol. 13, pp. 138-144, 1992 C ! C C ! C C ! C [4] R. Barrett et al C ! C Templates for the solution of linear systems C ! C SIAM, 1993 ! C C ! C C ! CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC ! File: psb_scgstab.f90 ! ! Subroutine: psb_scgstab ! This subroutine implements the BiCG Stabilized method. ! ! ! Arguments: ! ! a - type(psb_sspmat_type) Input: sparse matrix containing A. ! prec - class(psb_sprec_type) Input: preconditioner ! b - real,dimension(:) Input: vector containing the ! right hand side B ! x - real,dimension(:) 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_scgstab_vect(a,prec,b,x,eps,desc_a,info,itmax,iter,err,itrace,istop) 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 class(psb_sprec_type), Intent(inout) :: prec Type(psb_desc_type), Intent(in) :: desc_a 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 ! = Local data real(psb_spk_), allocatable, target :: aux(:),wwrk(:,:) type(psb_s_vect_type) :: q, r, p, v, s, t, z, f integer(psb_ipk_) :: itmax_, naux, it,itrace_,& & n_row, n_col integer(psb_lpk_) :: mglob integer(psb_ipk_) :: debug_level, debug_unit Logical, Parameter :: exchange=.True., noexchange=.False., debug1 = .False. integer(psb_ipk_), Parameter :: irmax = 8 integer(psb_ipk_) :: itx, err_act, i integer(psb_ipk_) :: istop_ type(psb_ctxt_type) :: ictxt integer(psb_ipk_) :: np, me real(psb_dpk_) :: derr real(psb_spk_) :: alpha, beta, rho, rho_old, sigma, omega, tau type(psb_itconv_type) :: stopdat character(len=20) :: name character(len=*), parameter :: methdname='BiCGStab' info = psb_success_ name = 'psb_scgstab' 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 (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),': from psb_info',np if (.not.allocated(x%v)) then info = psb_err_invalid_vect_state_ call psb_errpush(info,name) goto 9999 endif if (.not.allocated(b%v)) then info = psb_err_invalid_vect_state_ call psb_errpush(info,name) goto 9999 endif mglob = desc_a%get_global_rows() n_row = desc_a%get_local_rows() n_col = desc_a%get_local_cols() If (Present(istop)) Then istop_ = istop Else istop_ = 2 Endif ! ! ISTOP_ = 1: Normwise backward error, infinity norm ! ISTOP_ = 2: ||r||/||b|| norm 2 ! ! = if (.not.same_type_as(x,b)) then ! = write(0,*) 'Warning: different dynamic types for X and B ' ! = end if call psb_chkvect(mglob,lone,x%get_nrows(),lone,lone,desc_a,info) if (psb_errstatus_fatal()) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='psb_chkvect on X') goto 9999 end if call psb_chkvect(mglob,lone,b%get_nrows(),lone,lone,desc_a,info) if (psb_errstatus_fatal()) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='psb_chkvect on B') goto 9999 end if naux=6*n_col if (info == psb_success_) allocate(aux(naux),stat=info) if (info /= psb_success_) then info=psb_err_alloc_dealloc_ call psb_errpush(info,name) goto 9999 End If call psb_geasb(q,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(r,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(p,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(v,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(s,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(t,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(z,desc_a,info,mold=x%v,scratch=.true.) call psb_geasb(f,desc_a,info,mold=x%v,scratch=.true.) if (psb_errstatus_fatal()) then info=psb_err_from_subroutine_non_ call psb_errpush(info,name) goto 9999 End If If (Present(itmax)) Then itmax_ = itmax Else itmax_ = 1000 Endif If (Present(itrace)) Then itrace_ = itrace Else itrace_ = 0 End If itx = 0 call psb_init_conv(methdname,istop_,itrace_,itmax_,a,x,b,eps,desc_a,stopdat,info) if (psb_errstatus_fatal()) Then call psb_errpush(psb_err_from_subroutine_non_,name) goto 9999 End If restart: Do if (itx >= itmax_) exit restart it = 0 call psb_geaxpby(sone,b,szero,r,desc_a,info) call psb_spmm(-sone,a,x,sone,r,desc_a,info,work=aux) call psb_geaxpby(sone,r,szero,q,desc_a,info) ! Perhaps we already satisfy the convergence criterion... if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart if (psb_errstatus_fatal()) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='Init residual chk') goto 9999 end if rho = szero iteration: Do it = it + 1 itx = itx + 1 if (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),& & ' Iteration: ',itx rho_old = rho rho = psb_gedot(q,r,desc_a,info) if (debug_level >= psb_debug_ext_) then call q%sync() call r%sync() end if if (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),& & ' Rho: ',rho if (rho == szero) then if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Iteration breakdown R',rho exit iteration endif if (it == 1) then call psb_geaxpby(sone,r,szero,p,desc_a,info) else beta = (rho/rho_old)*(alpha/omega) call psb_geaxpby(-omega,v,sone,p,desc_a,info) call psb_geaxpby(sone,r,beta,p,desc_a,info) End If call prec%apply(p,f,desc_a,info,work=aux) call psb_spmm(sone,a,f,szero,v,desc_a,info,& & work=aux) sigma = psb_gedot(q,v,desc_a,info) if (debug_level >= psb_debug_ext_) then call q%sync() call v%sync() end if if (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),& & ' Sigma: ',sigma if (sigma == szero) then if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Iteration breakdown S1', sigma exit iteration endif alpha = rho/sigma call psb_geaxpby(sone,r,szero,s,desc_a,info) call psb_geaxpby(-alpha,v,sone,s,desc_a,info) if (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),& & ' alpha: ',alpha if (psb_errstatus_fatal()) then call psb_errpush(psb_err_from_subroutine_,name,a_err='psb_geaxpby') goto 9999 end if call prec%apply(s,z,desc_a,info,work=aux) Call psb_spmm(sone,a,z,szero,t,desc_a,info,work=aux) if(psb_errstatus_fatal()) then call psb_errpush(psb_err_from_subroutine_,name,a_err='precaply/spmm') goto 9999 end if sigma = psb_gedot(t,t,desc_a,info) if (sigma == szero) then if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Iteration breakdown S2', sigma exit iteration endif tau = psb_gedot(t,s,desc_a,info) omega = tau/sigma if (debug_level >= psb_debug_ext_) then call t%sync() call s%sync() end if if (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),& & ' sigma, tau, omega: ',sigma, tau, omega if (omega == szero) then if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Iteration breakdown O',omega exit iteration endif call psb_geaxpby(alpha,f,sone,x,desc_a,info) call psb_geaxpby(omega,z,sone,x,desc_a,info) call psb_geaxpby(sone,s,szero,r,desc_a,info) call psb_geaxpby(-omega,t,sone,r,desc_a,info) if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart if (psb_errstatus_fatal()) Then call psb_errpush(psb_err_from_subroutine_,name,a_err='X/R update ') 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 deallocate(aux,stat=info) call x%sync() call psb_gefree(q,desc_a,info) call psb_gefree(r,desc_a,info) call psb_gefree(p,desc_a,info) call psb_gefree(v,desc_a,info) call psb_gefree(s,desc_a,info) call psb_gefree(t,desc_a,info) call psb_gefree(z,desc_a,info) call psb_gefree(f,desc_a,info) if(psb_errstatus_fatal()) then call psb_errpush(info,name) goto 9999 end if call psb_erractionrestore(err_act) return 9999 call psb_error_handler(err_act) return End Subroutine psb_scgstab_vect