!!$ !!$ Parallel Sparse BLAS v2.0 !!$ (C) Copyright 2006 Salvatore Filippone University of Rome Tor Vergata !!$ Alfredo Buttari University of Rome Tor Vergata !!$ !!$ 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_zcgstab.f90 ! ! Subroutine: psb_zcgstab ! This subroutine implements the CG Stabilized method. ! ! Parameters: ! a - type(). The sparse matrix containing A. ! prec - type(). The data structure containing the ! preconditioner. ! b - real,dimension(:). The right hand side. ! x - real,dimension(:). The vector of unknowns. ! eps - real. The error tolerance. ! desc_a - type(). The communication descriptor. ! info - integer. Eventually returns an error code. ! itmax - integer(optional). The maximum number of iterations. ! iter - integer(optional). The number of iterations performed. ! err - real(optional). The error on return. ! itrace - integer(optional). The unit to write messages onto. ! istop - integer(optional). The stopping criterium. ! Subroutine psb_zcgstab(a,prec,b,x,eps,desc_a,info,& &itmax,iter,err,itrace, istop) use psb_base_mod use psb_prec_mod Implicit None !!$ parameters Type(psb_zspmat_type), Intent(in) :: a Type(psb_zprec_type), Intent(in) :: prec Type(psb_desc_type), Intent(in) :: desc_a Complex(Kind(1.d0)), Intent(in) :: b(:) Complex(Kind(1.d0)), Intent(inout) :: x(:) Real(Kind(1.d0)), Intent(in) :: eps integer, intent(out) :: info Integer, Optional, Intent(in) :: itmax, itrace, istop Integer, Optional, Intent(out) :: iter Real(Kind(1.d0)), Optional, Intent(out) :: err !!$ Local data Complex(Kind(1.d0)), allocatable, target :: aux(:),wwrk(:,:) Complex(Kind(1.d0)), Pointer :: q(:),& & r(:), p(:), v(:), s(:), t(:), z(:), f(:) Real(Kind(1.d0)) :: rerr Integer :: litmax, naux, m, mglob, it,itrace_,& & np,me, n_row, n_col Character ::diagl, diagu Logical, Parameter :: debug = .false. Logical, Parameter :: exchange=.True., noexchange=.False., debug1 = .False. Integer, Parameter :: irmax = 8 Integer :: itx, i, isvch, ich, ictxt, err_act, int_err(5),ii Integer :: istop_ complex(Kind(1.d0)) :: alpha, beta, rho, rho_old, sigma, omega, tau Real(Kind(1.d0)) :: rni, xni, bni, ani, rn0, bn2 !!$ Integer istpb, istpe, ifctb, ifcte, imerr, irank, icomm,immb,imme !!$ Integer mpe_log_get_event_number,mpe_Describe_state,mpe_log_event character(len=20) :: name info = 0 name = 'psb_zcgstab' call psb_erractionsave(err_act) If (debug) Write(*,*) 'Entering PSB_ZCGSTAB',present(istop) ictxt = psb_cd_get_context(desc_a) CALL psb_info(ictxt, me, np) if (debug) write(*,*) 'PSB_ZCGSTAB: From GRIDINFO',np,me mglob = psb_cd_get_global_rows(desc_a) n_row = psb_cd_get_local_rows(desc_a) n_col = psb_cd_get_local_cols(desc_a) If (Present(istop)) Then istop_ = istop Else istop_ = 1 Endif ! ! ISTOP = 1: Normwise backward error, infinity norm ! ISTOP = 2: ||r||/||b|| norm 2 ! if ((istop_ < 1 ).or.(istop_ > 2 ) ) then write(0,*) 'psb_bicgstab: invalid istop',istop_ info=5001 int_err(1)=istop_ err=info call psb_errpush(info,name,i_err=int_err) goto 9999 endif call psb_chkvect(mglob,1,size(x,1),1,1,desc_a,info) if(info /= 0) then info=4010 call psb_errpush(info,name,a_err='psb_chkvect on X') goto 9999 end if call psb_chkvect(mglob,1,size(b,1),1,1,desc_a,info) if(info /= 0) then info=4010 call psb_errpush(info,name,a_err='psb_chkvect on B') goto 9999 end if naux=6*n_col allocate(aux(naux),stat=info) if (info==0) call psb_geall(wwrk,desc_a,info,n=8) if (info==0) call psb_geasb(wwrk,desc_a,info) if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 End If Q => WWRK(:,1) R => WWRK(:,2) P => WWRK(:,3) V => WWRK(:,4) F => WWRK(:,5) S => WWRK(:,6) T => WWRK(:,7) Z => WWRK(:,8) If (Present(itmax)) Then litmax = itmax Else litmax = 1000 Endif If (Present(itrace)) Then itrace_ = itrace Else itrace_ = 0 End If diagl = 'U' diagu = 'U' ! Ensure global coherence for convergence checks. call psb_set_coher(ictxt,isvch) itx = 0 If (istop_ == 1) Then ani = psb_spnrmi(a,desc_a,info) bni = psb_geamax(b,desc_a,info) Else If (istop_ == 2) Then bn2 = psb_genrm2(b,desc_a,info) Endif if (info /= 0) Then info=4011 call psb_errpush(info,name) goto 9999 End If restart: Do !!$ !!$ r0 = b-Ax0 !!$ If (itx >= litmax) Exit restart it = 0 Call psb_geaxpby(zone,b,zzero,r,desc_a,info) Call psb_spmm(-zone,a,x,zone,r,desc_a,info,work=aux) Call psb_geaxpby(zone,r,zzero,q,desc_a,info) if (info /= 0) Then info=4011 call psb_errpush(info,name) goto 9999 End If rho = zzero If (debug) Write(*,*) 'On entry to AMAX: B: ',Size(b) ! ! Must always provide norm of R into RNI below for first check on ! residual ! If (istop_ == 1) Then rni = psb_geamax(r,desc_a,info) xni = psb_geamax(x,desc_a,info) Else If (istop_ == 2) Then rni = psb_genrm2(r,desc_a,info) Endif if (info /= 0) Then info=4011 call psb_errpush(info,name) goto 9999 End If If (itx == 0) Then rn0 = rni End If If (rn0 == 0.d0 ) Then Exit restart End If If (istop_ == 1) Then xni = psb_geamax(x,desc_a,info) rerr = rni/(ani*xni+bni) Else If (istop_ == 2) Then rerr = rni/bn2 Endif if (info /= 0) Then info=4011 call psb_errpush(info,name) goto 9999 End If If (rerr<=eps) Then Exit restart End If If (itrace_ > 0) then if ((mod(itx,itrace_)==0).and.(me == 0))& & write(*,'(a,i4,3(2x,es10.4))') 'bicgstab: ',itx,rerr end If iteration: Do it = it + 1 itx = itx + 1 If (debug) Write(*,*) 'Iteration: ',itx rho_old = rho rho = psb_gedot(q,r,desc_a,info) If (rho==zzero) Then If (debug) Write(0,*) 'Bi-CGSTAB Itxation breakdown R',rho Exit iteration Endif If (it==1) Then Call psb_geaxpby(zone,r,zzero,p,desc_a,info) Else beta = (rho/rho_old)*(alpha/omega) Call psb_geaxpby(-omega,v,zone,p,desc_a,info) Call psb_geaxpby(zone,r,beta,p,desc_a,info) End If Call psb_precaply(prec,p,f,desc_a,info,work=aux) Call psb_spmm(zone,a,f,zzero,v,desc_a,info,& & work=aux) sigma = psb_gedot(q,v,desc_a,info) If (sigma==zzero) Then If (debug) Write(0,*) 'Bi-CGSTAB Iteration breakdown S1', sigma Exit iteration Endif alpha = rho/sigma Call psb_geaxpby(zone,r,zzero,s,desc_a,info) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_geaxpby') goto 9999 end if Call psb_geaxpby(-alpha,v,zone,s,desc_a,info) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_geaxpby') goto 9999 end if Call psb_precaply(prec,s,z,desc_a,info,work=aux) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_precaply') goto 9999 end if Call psb_spmm(zone,a,z,zzero,t,desc_a,info,& & work=aux) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_spmm') goto 9999 end if sigma = psb_gedot(t,t,desc_a,info) If (sigma==zzero) Then If (debug) Write(0,*) 'BI-CGSTAB ITERATION BREAKDOWN S2', sigma Exit iteration Endif tau = psb_gedot(t,s,desc_a,info) omega = tau/sigma If (omega==zzero) Then If (debug) Write(0,*) 'BI-CGSTAB ITERATION BREAKDOWN O',omega Exit iteration Endif Call psb_geaxpby(alpha,f,zone,x,desc_a,info) Call psb_geaxpby(omega,z,zone,x,desc_a,info) Call psb_geaxpby(zone,s,zzero,r,desc_a,info) Call psb_geaxpby(-omega,t,zone,r,desc_a,info) If (istop_ == 1) Then rni = psb_geamax(r,desc_a,info) xni = psb_geamax(x,desc_a,info) rerr = rni/(ani*xni+bni) Else If (istop_ == 2) Then rni = psb_genrm2(r,desc_a,info) rerr = rni/bn2 Endif If (rerr<=eps) Then Exit restart End If If (itx.Ge.litmax) Exit restart If (itrace_ > 0) then if ((mod(itx,itrace_)==0).and.(me == 0))& & write(*,'(a,i4,3(2x,es10.4))') 'bicgstab: ',itx,rerr end If End Do iteration End Do restart If (itrace_ > 0) then if (me == 0) write(*,'(a,i4,3(2x,es10.4))') 'bicgstab: ',itx,rerr end If If (Present(err)) err=rerr If (Present(iter)) iter = itx If (rerr>eps) Then Write(0,*) 'BI-cgstab failed to converge to ',eps,& & ' in ',itx,' iterations. ' End If Deallocate(aux) Call psb_gefree(wwrk,desc_a,info) ! restore external global coherence behaviour call psb_restore_coher(ictxt,isvch) !!$ imerr = MPE_Log_event( istpe, 0, "ed CGSTAB" ) if(info/=0) then call psb_errpush(info,name) goto 9999 end if call psb_erractionrestore(err_act) return 9999 continue call psb_erractionrestore(err_act) if (err_act.eq.psb_act_abort_) then call psb_error(ictxt) return end if return End Subroutine psb_zcgstab