!!$ !!$ 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_dcgstab.f90 ! ! Subroutine: psb_dcgstab ! 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_dcgstab(a,prec,b,x,eps,desc_a,info,& &itmax,iter,err,itrace, istop) use psb_serial_mod use psb_descriptor_type use psb_prec_type use psb_psblas_mod use psb_tools_mod use psb_const_mod use psb_prec_mod use psb_error_mod Implicit None !!$ parameters Type(psb_dspmat_type), Intent(in) :: a Type(psb_dprec_type), Intent(in) :: prec Type(psb_desc_type), Intent(in) :: desc_a Real(Kind(1.d0)), Intent(in) :: b(:) Real(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 Real(Kind(1.d0)), Pointer :: aux(:),wwrk(:,:) Real(Kind(1.d0)), Pointer :: q(:),& & r(:), p(:), v(:), s(:), t(:), z(:), f(:) Integer, Pointer :: iperm(:), ipnull(:), ipsave(:) Real(Kind(1.d0)) ::rerr Integer ::litmax, liter, naux, m, mglob, it,itrac,& & nprows,npcols,myrow,mycol, 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, icontxt, err_act, int_err(5),ii Integer :: listop Logical :: do_renum_left Real(Kind(1.d0)), Parameter :: one=1.d0, zero=0.d0, epstol=1.d-35 Real(Kind(1.d0)) :: alpha, beta, rho, rho_old, rni, xni, bni, ani,& & sigma, omega, tau, 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,ch_err info = 0 name = 'psb_dcgstab' call psb_erractionsave(err_act) If (debug) Write(*,*) 'Entering PSB_DCGSTAB',present(istop) icontxt = desc_a%matrix_data(psb_ctxt_) CALL blacs_gridinfo(icontxt,nprows,npcols,myrow,mycol) if (debug) write(*,*) 'PSB_DCGSTAB: From GRIDINFO',nprows,npcols,myrow mglob = desc_a%matrix_data(psb_m_) n_row = desc_a%matrix_data(psb_n_row_) n_col = desc_a%matrix_data(psb_n_col_) If (Present(istop)) Then listop = istop Else listop = 1 Endif ! ! LISTOP = 1: Normwise backward error, infinity norm ! LISTOP = 2: ||r||/||b|| norm 2 ! If ((prec%prec < min_prec_).Or.(prec%prec > max_prec_) ) Then Write(0,*) 'PSB_CGSTAB: Invalid IPREC',prec%prec info=5002 int_err(1)=prec%prec err=info call psb_errpush(info,name,i_err=int_err) goto 9999 Endif if ((listop < 1 ).or.(listop > 2 ) ) then write(0,*) 'psb_bicgstab: invalid istop',listop info=5001 int_err(1)=listop err=info call psb_errpush(info,name,i_err=int_err) goto 9999 endif naux=6*n_col allocate(aux(naux),stat=info) call psb_alloc(mglob,8,wwrk,desc_a,info) call psb_asb(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 itrac = itrace Else itrac = -1 End If diagl = 'U' diagu = 'U' ! Ensure global coherence for convergence checks. Call blacs_get(icontxt,16,isvch) ich = 1 Call blacs_set(icontxt,16,ich) itx = 0 If (listop == 1) Then ani = psb_nrmi(a,desc_a,info) bni = psb_amax(b,desc_a,info) Else If (listop == 2) Then bn2 = psb_nrm2(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_axpby(one,b,zero,r,desc_a,info) Call psb_spmm(-one,a,x,one,r,desc_a,info,work=aux) Call psb_axpby(one,r,zero,q,desc_a,info) if (info /= 0) Then info=4011 call psb_errpush(info,name) goto 9999 End If rho = zero 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 (listop == 1) Then rni = psb_amax(r,desc_a,info) xni = psb_amax(x,desc_a,info) Else If (listop == 2) Then rni = psb_nrm2(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 If (itrac /= -1) Then If (myrow == 0) Write(itrac,*) 'BiCGSTAB: ',itx,rn0 Endif Exit restart End If If (listop == 1) Then xni = psb_amax(x,desc_a,info) rerr = rni/(ani*xni+bni) If (itrac /= -1) Then If (myrow == 0) Write(itrac,'(a,i4,5(2x,es10.4))') 'bicgstab: ',itx,rerr,rni,bni,& &xni,ani Endif Else If (listop == 2) Then rerr = rni/bn2 If (itrac /= -1) Then If (myrow == 0) Write(itrac,'(a,i4,3(2x,es10.4))') 'bicgstab: ',itx,rerr,rni,bn2 Endif Endif if (info /= 0) Then info=4011 call psb_errpush(info,name) goto 9999 End If If (rerr<=eps) Then Exit restart End If iteration: Do it = it + 1 itx = itx + 1 If (debug) Write(*,*) 'Iteration: ',itx rho_old = rho rho = psb_dot(q,r,desc_a,info) !!$ call blacs_barrier(icontxt,'All') ! to be removed !!$ write(0,'(i2," rho old ",2(f,2x))')myrow,rho,rho_old !!$ call blacs_barrier(icontxt,'All') ! to be removed If (rho==zero) Then If (debug) Write(0,*) 'Bi-CGSTAB Itxation breakdown R',rho Exit iteration Endif If (it==1) Then Call psb_axpby(one,r,zero,p,desc_a,info) Else beta = (rho/rho_old)*(alpha/omega) Call psb_axpby(-omega,v,one,p,desc_a,info) Call psb_axpby(one,r,beta,p,desc_a,info) End If Call psb_prcaply(prec,p,f,desc_a,info,work=aux) Call psb_spmm(one,a,f,zero,v,desc_a,info,& & work=aux) sigma = psb_dot(q,v,desc_a,info) If (sigma==zero) Then If (debug) Write(0,*) 'Bi-CGSTAB Iteration breakdown S1', sigma Exit iteration Endif alpha = rho/sigma Call psb_axpby(one,r,zero,s,desc_a,info) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_axpby') goto 9999 end if Call psb_axpby(-alpha,v,one,s,desc_a,info) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_axpby') goto 9999 end if Call psb_prcaply(prec,s,z,desc_a,info,work=aux) if(info.ne.0) then call psb_errpush(4010,name,a_err='psb_prcaply') goto 9999 end if Call psb_spmm(one,a,z,zero,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_dot(t,t,desc_a,info) If (sigma==zero) Then If (debug) Write(0,*) 'BI-CGSTAB ITERATION BREAKDOWN S2', sigma Exit iteration Endif tau = psb_dot(t,s,desc_a,info) omega = tau/sigma If (omega==zero) Then If (debug) Write(0,*) 'BI-CGSTAB ITERATION BREAKDOWN O',omega Exit iteration Endif Call psb_axpby(alpha,f,one,x,desc_a,info) Call psb_axpby(omega,z,one,x,desc_a,info) Call psb_axpby(one,s,zero,r,desc_a,info) Call psb_axpby(-omega,t,one,r,desc_a,info) If (listop == 1) Then rni = psb_amax(r,desc_a,info) xni = psb_amax(x,desc_a,info) rerr = rni/(ani*xni+bni) If (itrac /= -1) Then If (myrow == 0) Write(itrac,'(a,i4,5(2x,es10.4))') 'bicgstab: ',itx,rerr,rni,bni,& &xni,ani Endif Else If (listop == 2) Then rni = psb_nrm2(r,desc_a,info) rerr = rni/bn2 If (itrac /= -1) Then If (myrow == 0) Write(itrac,'(a,i4,3(2x,es10.4)))') 'bicgstab: ',itx,rerr,rni,bn2 Endif Endif If (rerr<=eps) Then Exit restart End If If (itx.Ge.litmax) Exit restart End Do iteration End Do restart 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_free(wwrk,desc_a,info) ! restore external global coherence behaviour Call blacs_set(icontxt,16,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.act_abort) then call psb_error(icontxt) return end if return End Subroutine psb_dcgstab