!!$ !!$ Parallel Sparse BLAS version 2.2 !!$ (C) Copyright 2006/2007/2008 !!$ Salvatore Filippone University of Rome Tor Vergata !!$ Alfredo Buttari University of Rome Tor Vergata !!$ !!$ Contributions to this routine: !!$ Daniela di Serafino Second University of Naples !!$ Pasqua D'Ambra ICAR-CNR !!$ !!$ 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 C !!$ C [5] G. Sleijpen, D. Fokkema C !!$ C BICGSTAB(L) for linear equations involving unsymmetric C !!$ C matrices with complex spectrum C !!$ C Electronic Trans. on Numer. Analysis, Vol. 1, pp. 11-32, C !!$ C Sep. 1993 C !!$ C C !!$ C C !!$ CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC ! File: psb_srgmres.f90 ! ! Subroutine: psb_srgmres ! This subroutine implements the restarted GMRES method with right ! preconditioning. ! ! Arguments: ! ! a - type(psb_s_sparse_mat) 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|/|b|; here the iteration is ! stopped when |r| <= eps * |b| ! 2: err = |r|/(|a||x|+|b|); here the iteration is ! stopped when |r| <= eps * (|a||x|+|b|) ! where r is the (preconditioned, recursive ! estimate of) residual. ! irst - integer(optional) Input: restart parameter ! ! subroutine psb_srgmres(a,prec,b,x,eps,desc_a,info,itmax,iter,err,itrace,irst,istop) use psb_sparse_mod use psb_prec_mod use psb_krylov_mod, psb_protect_name => psb_srgmres implicit none !!$ Parameters Type(psb_s_sparse_mat), Intent(in) :: a class(psb_sprec_type), Intent(in) :: prec Type(psb_desc_type), Intent(in) :: desc_a Real(psb_spk_), Intent(in) :: b(:) Real(psb_spk_), Intent(inout) :: x(:) Real(psb_spk_), Intent(in) :: eps integer, intent(out) :: info Integer, Optional, Intent(in) :: itmax, itrace, irst,istop Integer, Optional, Intent(out) :: iter Real(psb_spk_), Optional, Intent(out) :: err !!$ local data Real(psb_spk_), allocatable, target :: aux(:),w(:),w1(:), v(:,:) Real(psb_spk_), allocatable :: c(:),s(:), h(:,:), rs(:),rst(:),xt(:) Real(psb_spk_) :: scal, gm, rti, rti1 Integer ::litmax, naux, mglob, it,k, itrace_,& & np,me, n_row, n_col, nl, int_err(5) Logical, Parameter :: exchange=.True., noexchange=.False. Integer, Parameter :: irmax = 8 Integer :: itx, i, isvch, ictxt,istop_, err_act integer :: debug_level, debug_unit Real(psb_spk_) :: rni, xni, bni, ani,bn2, dt real(psb_dpk_) :: errnum, errden, deps, derr character(len=20) :: name character(len=*), parameter :: methdname='RGMRES' info = 0 name = 'psb_sgmres' call psb_erractionsave(err_act) debug_unit = psb_get_debug_unit() debug_level = psb_get_debug_level() ictxt = psb_cd_get_context(desc_a) Call psb_info(ictxt, me, np) if (debug_level >= psb_debug_ext_)& & write(debug_unit,*) me,' ',trim(name),': from psb_info',np 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_ = 2 endif ! ! ISTOP_ = 1: Normwise backward error, infinity norm ! ISTOP_ = 2: ||r||/||b||, 2-norm ! if ((istop_ < 1 ).or.(istop_ > 2 ) ) then info=5001 int_err(1)=istop_ err=info call psb_errpush(info,name,i_err=int_err) goto 9999 endif if (present(itmax)) then litmax = itmax else litmax = 1000 endif if (present(itrace)) then itrace_ = itrace else itrace_ = 0 end if if (present(irst)) then nl = irst if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' present: irst: ',irst,nl else nl = 10 if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' not present: irst: ',irst,nl endif if (nl <=0 ) then info=5001 int_err(1)=nl 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=4*n_col allocate(aux(naux),h(nl+1,nl+1),& &c(nl+1),s(nl+1),rs(nl+1), rst(nl+1),stat=info) if (info == 0) call psb_geall(v,desc_a,info,n=nl+1) if (info == 0) call psb_geall(w,desc_a,info) if (info == 0) call psb_geall(w1,desc_a,info) if (info == 0) call psb_geall(xt,desc_a,info) if (info == 0) call psb_geasb(v,desc_a,info) if (info == 0) call psb_geasb(w,desc_a,info) if (info == 0) call psb_geasb(w1,desc_a,info) if (info == 0) call psb_geasb(xt,desc_a,info) if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Size of V,W,W1 ',size(v),size(v,1),& & size(w),size(w,1),size(w1),size(w1,1), size(v(:,1)) ! Ensure global coherence for convergence checks. call psb_set_coher(ictxt,isvch) 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 errnum = dzero errden = done deps = eps if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if if ((itrace_ > 0).and.(me==0)) call log_header(methdname) itx = 0 restart: do ! compute r0 = b-ax0 ! check convergence ! compute v1 = r0/||r0||_2 if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' restart: ',itx,it it = 0 call psb_geaxpby(sone,b,szero,v(:,1),desc_a,info) if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if call psb_spmm(-sone,a,x,sone,v(:,1),desc_a,info,work=aux) if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if rs(1) = psb_genrm2(v(:,1),desc_a,info) rs(2:) = szero if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if scal=sone/rs(1) ! rs(1) MIGHT BE VERY SMALL - USE DSCAL TO DEAL WITH IT? if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' on entry to amax: b: ',Size(b),rs(1),scal ! ! check convergence ! if (istop_ == 1) then rni = psb_geamax(v(:,1),desc_a,info) xni = psb_geamax(x,desc_a,info) errnum = rni errden = (ani*xni+bni) else if (istop_ == 2) then rni = psb_genrm2(v(:,1),desc_a,info) errnum = rni errden = bn2 endif if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if if (errnum <= eps*errden) exit restart if (itrace_ > 0) & & call log_conv(methdname,me,itx,itrace_,errnum,errden,deps) v(:,1) = v(:,1) * scal if (itx >= litmax) exit restart ! ! inner iterations ! inner: Do i=1,nl itx = itx + 1 call prec%apply(v(:,i),w1,desc_a,info) call psb_spmm(sone,a,w1,szero,w,desc_a,info,work=aux) ! do k = 1, i h(k,i) = psb_gedot(v(:,k),w,desc_a,info) call psb_geaxpby(-h(k,i),v(:,k),sone,w,desc_a,info) end do h(i+1,i) = psb_genrm2(w,desc_a,info) scal=sone/h(i+1,i) call psb_geaxpby(scal,w,szero,v(:,i+1),desc_a,info) do k=2,i call srot(1,h(k-1,i),1,h(k,i),1,c(k-1),s(k-1)) enddo rti = h(i,i) rti1 = h(i+1,i) call srotg(rti,rti1,c(i),s(i)) call srot(1,h(i,i),1,h(i+1,i),1,c(i),s(i)) h(i+1,i) = szero call srot(1,rs(i),1,rs(i+1),1,c(i),s(i)) if (istop_ == 1) then ! ! build x and then compute the residual and its infinity norm ! rst = rs xt = szero call strsm('l','u','n','n',i,1,sone,h,size(h,1),rst,size(rst,1)) if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Rebuild x-> RS:',rst(1:nl) do k=1, i call psb_geaxpby(rst(k),v(:,k),sone,xt,desc_a,info) end do call prec%apply(xt,desc_a,info) call psb_geaxpby(sone,x,sone,xt,desc_a,info) call psb_geaxpby(sone,b,szero,w1,desc_a,info) call psb_spmm(-sone,a,xt,sone,w1,desc_a,info,work=aux) rni = psb_geamax(w1,desc_a,info) xni = psb_geamax(xt,desc_a,info) errnum = rni errden = (ani*xni+bni) ! else if (istop_ == 2) then ! ! compute the residual 2-norm as byproduct of the solution ! procedure of the least-squares problem ! rni = abs(rs(i+1)) errnum = rni errden = bn2 endif if (errnum <= eps*errden) then if (istop_ == 1) then x = xt else if (istop_ == 2) then ! ! build x ! if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Rebuild RS:',rs(1:i) if ((debug_level >= psb_debug_ext_).and.(me==0)) then write(debug_unit,*) me,' ',trim(name),& & ' Rebuild RS H:' do k=1,i write(debug_unit,*) h(k,1:i) end do end if call strsm('l','u','n','n',i,1,sone,h,size(h,1),rs,size(rs,1)) if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Rebuild x-> RS:',rs(1:nl) w1 = szero do k=1, i call psb_geaxpby(rs(k),v(:,k),sone,w1,desc_a,info) end do call prec%apply(w1,w,desc_a,info) call psb_geaxpby(sone,w,sone,x,desc_a,info) end if exit restart end if if (itrace_ > 0) & & call log_conv(methdname,me,itx,itrace_,errnum,errden,deps) end do inner if (istop_ == 1) then x = xt else if (istop_ == 2) then ! ! build x ! if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Rebuild RS:',rs(1:nl) call strsm('l','u','n','n',nl,1,sone,h,size(h,1),rs,size(rs,1)) if (debug_level >= psb_debug_ext_) & & write(debug_unit,*) me,' ',trim(name),& & ' Rebuild x-> RS:',rs(1:nl) w1 = szero do k=1, nl call psb_geaxpby(rs(k),v(:,k),sone,w1,desc_a,info) end do call prec%apply(w1,w,desc_a,info) call psb_geaxpby(sone,w,sone,x,desc_a,info) end if end do restart if (itrace_ > 0) & & call log_conv(methdname,me,itx,1,errnum,errden,deps) call log_end(methdname,me,itx,errnum,errden,deps,err=derr,iter=iter) if (present(err)) then err = derr end if deallocate(aux,h,c,s,rs,rst, stat=info) if (info == 0) call psb_gefree(v,desc_a,info) if (info == 0) call psb_gefree(w,desc_a,info) if (info == 0) call psb_gefree(w1,desc_a,info) if (info == 0) call psb_gefree(xt,desc_a,info) if (info /= 0) then info=4011 call psb_errpush(info,name) goto 9999 end if ! restore external global coherence behaviour call psb_restore_coher(ictxt,isvch) call psb_erractionrestore(err_act) return 9999 continue call psb_erractionrestore(err_act) if (err_act == psb_act_abort_) then call psb_error() return end if return end subroutine psb_srgmres