!
! 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
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! 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_zcgs.f90
!
! Subroutine: psb_zcgs
! Implements the Conjugate Gradient Squared method.
!
! Arguments:
!
! a - type(psb_zspmat_type) Input: sparse matrix containing A.
! prec - class(psb_zprec_type) Input: preconditioner
! b - complex,dimension(:) Input: vector containing the
! right hand side B
! x - complex,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_zcgs_vect(a,prec,b,x,eps,desc_a,info,&
& itmax,iter,err,itrace,istop)
use psb_base_mod
use psb_prec_mod
use psb_z_krylov_conv_mod
use psb_krylov_mod
implicit none
type(psb_zspmat_type), intent(in) :: a
Type(psb_desc_type), Intent(in) :: desc_a
class(psb_zprec_type), intent(inout) :: prec
type(psb_z_vect_type), Intent(inout) :: b
type(psb_z_vect_type), Intent(inout) :: x
Real(psb_dpk_), 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_dpk_), Optional, Intent(out) :: err
! = local data
complex(psb_dpk_), allocatable, target :: aux(:)
type(psb_z_vect_type), allocatable, target :: wwrk(:)
type(psb_z_vect_type), pointer :: ww, q, r, p, v,&
& s, z, f, rt, qt, uv
integer(psb_ipk_) :: itmax_, naux, mglob, it, itrace_,int_err(5),&
& n_row, n_col,istop_, itx, err_act
integer(psb_ipk_) :: np, me, ictxt
integer(psb_ipk_) :: debug_level, debug_unit
complex(psb_dpk_) :: alpha, beta, rho, rho_old, sigma
real(psb_dpk_) :: derr
type(psb_itconv_type) :: stopdat
character(len=20) :: name
character(len=*), parameter :: methdname='CGS'
info = psb_success_
name = 'psb_zcgs'
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(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_row = desc_a%get_local_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 (info == psb_success_) Call psb_geall(wwrk,desc_a,info,n=11_psb_ipk_)
if (info == psb_success_) Call psb_geasb(wwrk,desc_a,info,mold=x%v)
if (info /= psb_success_) Then
info=psb_err_from_subroutine_non_
call psb_errpush(info,name)
goto 9999
End If
q => wwrk(1)
qt => wwrk(2)
r => wwrk(3)
rt => wwrk(4)
p => wwrk(5)
v => wwrk(6)
uv => wwrk(7)
z => wwrk(8)
f => wwrk(9)
s => wwrk(10)
ww => wwrk(11)
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 (info /= psb_success_) Then
call psb_errpush(psb_err_from_subroutine_non_,name)
goto 9999
End If
restart: Do
! =
! = r0 = b-ax0
! =
if (itx >= itmax_) exit restart
it = 0
call psb_geaxpby(zone,b,zzero,r,desc_a,info)
if (info == psb_success_) call psb_spmm(-zone,a,x,zone,r,desc_a,info,work=aux)
if (info == psb_success_) call psb_geaxpby(zone,r,zzero,rt,desc_a,info)
if (info /= psb_success_) then
info=psb_err_from_subroutine_non_
call psb_errpush(info,name)
goto 9999
end if
! Perhaps we already satisfy the convergence criterion...
if (psb_check_conv(methdname,itx,x,r,desc_a,stopdat,info)) exit restart
if (info /= psb_success_) Then
call psb_errpush(psb_err_from_subroutine_non_,name)
goto 9999
End If
rho = zzero
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(rt,r,desc_a,info)
if (rho == zzero) 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(zone,r,zzero,uv,desc_a,info)
if (info == psb_success_) call psb_geaxpby(zone,r,zzero,p,desc_a,info)
else
beta = (rho/rho_old)
call psb_geaxpby(zone,r,zzero,uv,desc_a,info)
if (info == psb_success_) call psb_geaxpby(beta,q,zone,uv,desc_a,info)
if (info == psb_success_) call psb_geaxpby(zone,q,beta,p,desc_a,info)
if (info == psb_success_) call psb_geaxpby(zone,uv,beta,p,desc_a,info)
end if
if (info == psb_success_) call prec%apply(p,f,desc_a,info,work=aux)
if (info == psb_success_) call psb_spmm(zone,a,f,zzero,v,desc_a,info,&
& work=aux)
if (info /= psb_success_) then
call psb_errpush(psb_err_from_subroutine_,name,a_err='First loop part ')
goto 9999
end if
sigma = psb_gedot(rt,v,desc_a,info)
if (sigma == zzero) then
if (debug_level >= psb_debug_ext_) &
& write(debug_unit,*) me,' ',trim(name),&
& ' iteration breakdown s1', sigma
exit iteration
endif
alpha = rho/sigma
if (info == psb_success_) call psb_geaxpby(zone,uv,zzero,q,desc_a,info)
if (info == psb_success_) call psb_geaxpby(-alpha,v,zone,q,desc_a,info)
if (info == psb_success_) call psb_geaxpby(zone,uv,zzero,s,desc_a,info)
if (info == psb_success_) call psb_geaxpby(zone,q,zone,s,desc_a,info)
if (info == psb_success_) call prec%apply(s,z,desc_a,info,work=aux)
if (info == psb_success_) call psb_geaxpby(alpha,z,zone,x,desc_a,info)
if (info == psb_success_) call psb_spmm(zone,a,z,zzero,qt,desc_a,info,&
& work=aux)
if (info == psb_success_) call psb_geaxpby(-alpha,qt,zone,r,desc_a,info)
if (info /= psb_success_) then
call psb_errpush(psb_err_from_subroutine_,name,a_err='X update ')
goto 9999
end if
if (psb_check_conv(methdname,itx,x,r,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
if (info == psb_success_) call psb_gefree(wwrk,desc_a,info)
if (info == psb_success_) deallocate(aux,stat=info)
if (info /= psb_success_) 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_zcgs_vect