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amg4psblas/examples/pdegen/mld_sexample_ml.f90

369 lines
11 KiB
Fortran

!!$
!!$
!!$ MLD2P4 version 2.1
!!$ MultiLevel Domain Decomposition Parallel Preconditioners Package
!!$ based on PSBLAS (Parallel Sparse BLAS version 3.4)
!!$
!!$ (C) Copyright 2008, 2010, 2012, 2015, 2017
!!$
!!$ Salvatore Filippone Cranfield University
!!$ Ambra Abdullahi Hassan University of Rome Tor Vergata
!!$ Alfredo Buttari CNRS-IRIT, Toulouse
!!$ Pasqua D'Ambra ICAR-CNR, Naples
!!$ Daniela di Serafino University of Campania "L. Vanvitelli", Caserta
!!$
!!$ 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 MLD2P4 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 MLD2P4 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.
!!$
!!$
! File: mld_sexample_ml.f90
!
! This sample program solves a linear system obtained by discretizing a
! PDE with Dirichlet BCs. The solver is BiCGStab coupled with one of the
! following multi-level preconditioner, as explained in Section 6.1 of
! the MLD2P4 User's and Reference Guide:
! - choice = 1, default multi-level Schwarz preconditioner (Sec. 6.1, Fig. 2)
! - choice = 2, hybrid three-level Schwarz preconditioner (Sec. 6.1, Fig. 3)
! - choice = 3, additive three-level Schwarz preconditioner (Sec. 6.1, Fig. 4)
!
! The PDE is a general second order equation in 3d
!
! a1 dd(u) a2 dd(u) a3 dd(u) b1 d(u) b2 d(u) b3 d(u)
! - ------ - ------ - ------ + ----- + ------ + ------ + c u = f
! dxdx dydy dzdz dx dy dz
!
! with Dirichlet boundary conditions
! u = g
!
! on the unit cube 0<=x,y,z<=1.
!
!
! Note that if b1=b2=b3=c=0., the PDE is the Laplace equation.
!
! In this sample program the index space of the discretized
! computational domain is first numbered sequentially in a standard way,
! then the corresponding vector is distributed according to a BLOCK
! data distribution.
!
module spde_mod
contains
!
! functions parametrizing the differential equation
!
function b1(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: b1
real(psb_spk_), intent(in) :: x,y,z
b1=1.e0/sqrt(3.e0)
end function b1
function b2(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: b2
real(psb_spk_), intent(in) :: x,y,z
b2=1.e0/sqrt(3.e0)
end function b2
function b3(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: b3
real(psb_spk_), intent(in) :: x,y,z
b3=1.e0/sqrt(3.e0)
end function b3
function c(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: c
real(psb_spk_), intent(in) :: x,y,z
c=0.e0
end function c
function a1(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: a1
real(psb_spk_), intent(in) :: x,y,z
a1=1.e0/80
end function a1
function a2(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: a2
real(psb_spk_), intent(in) :: x,y,z
a2=1.e0/80
end function a2
function a3(x,y,z)
use psb_base_mod, only : psb_spk_
real(psb_spk_) :: a3
real(psb_spk_), intent(in) :: x,y,z
a3=1.e0/80
end function a3
function g(x,y,z)
use psb_base_mod, only : psb_spk_, sone, szero
real(psb_spk_) :: g
real(psb_spk_), intent(in) :: x,y,z
g = szero
if (x == sone) then
g = sone
else if (x == szero) then
g = exp(y**2-z**2)
end if
end function g
end module spde_mod
program mld_sexample_ml
use psb_base_mod
use mld_prec_mod
use psb_krylov_mod
use psb_util_mod
use data_input
use spde_mod
implicit none
! input parameters
! sparse matrices
type(psb_sspmat_type) :: A
! sparse matrices descriptor
type(psb_desc_type):: desc_A
! preconditioner
type(mld_sprec_type) :: P
! right-hand side, solution and residual vectors
type(psb_s_vect_type) :: x, b, r
! solver and preconditioner parameters
real(psb_spk_) :: tol, err
integer :: itmax, iter, istop
integer :: nlev
! parallel environment parameters
integer :: ictxt, iam, np
! other variables
integer :: choice
integer :: i,info,j
integer(psb_long_int_k_) :: amatsize, precsize, descsize
integer :: idim, ierr, ircode
real(psb_dpk_) :: t1, t2, tprec
real(psb_spk_) :: resmx, resmxp
character(len=5) :: afmt='CSR'
character(len=20) :: name
! initialize the parallel environment
call psb_init(ictxt)
call psb_info(ictxt,iam,np)
if (iam < 0) then
! This should not happen, but just in case
call psb_exit(ictxt)
stop
endif
!
! Hello world
!
if (iam == psb_root_) then
write(*,*) 'Welcome to MLD2P4 version: ',mld_version_string_
write(*,*) 'This is the ',trim(name),' sample program'
end if
name='mld_sexample_ml'
if(psb_get_errstatus() /= 0) goto 9999
info=psb_success_
call psb_set_errverbosity(2)
! get parameters
call get_parms(ictxt,choice,idim,itmax,tol)
! allocate and fill in the coefficient matrix, rhs and initial guess
call psb_barrier(ictxt)
t1 = psb_wtime()
call psb_gen_pde3d(ictxt,idim,a,b,x,desc_a,afmt,&
& a1,a2,a3,b1,b2,b3,c,g,info)
call psb_barrier(ictxt)
t2 = psb_wtime() - t1
if(info /= psb_success_) then
info=psb_err_from_subroutine_
call psb_errpush(info,name)
goto 9999
end if
if (iam == psb_root_) write(*,'("Overall matrix creation time : ",es12.5)')t2
if (iam == psb_root_) write(*,'(" ")')
select case(choice)
case(1)
! initialize the default multi-level preconditioner, i.e. hybrid
! Schwarz, using RAS (with overlap 1 and ILU(0) on the blocks)
! as post-smoother and 4 block-Jacobi sweeps (with UMFPACK LU
! on the blocks) as distributed coarse-level solver
call mld_precinit(P,'ML',info)
case(2)
! set a three-level hybrid Schwarz preconditioner, which uses
! block Jacobi (with ILU(0) on the blocks) as post-smoother,
! a coarsest matrix replicated on the processors, and the
! LU factorization from UMFPACK as coarse-level solver
call mld_precinit(P,'ML',info,nlev=3)
call mld_precset(P,mld_smoother_type_,'BJAC',info)
call mld_precset(P,mld_coarse_mat_,'REPL',info)
call mld_precset(P,mld_coarse_solve_,'UMF',info)
case(3)
! set a three-level additive Schwarz preconditioner, which uses
! RAS (with overlap 1 and ILU(0) on the blocks) as pre- and
! post-smoother, and 5 block-Jacobi sweeps (with UMFPACK LU
! on the blocks) as distributed coarsest-level solver
call mld_precinit(P,'ML',info,nlev=3)
call mld_precset(P,mld_ml_type_,'ADD',info)
call mld_precset(P,mld_smoother_pos_,'TWOSIDE',info)
call mld_precset(P,mld_coarse_sweeps_,5,info)
case(4)
! set a three-level hybrid Schwarz preconditioner, which uses
! block Jacobi (with ILU(0) on the blocks) as post-smoother,
! a coarsest matrix replicated on the processors, and the
! multifrontal solver from MUMPS as global coarse-level solver
call mld_precinit(P,'ML',info,nlev=3)
call mld_precset(P,mld_smoother_type_,'BJAC',info)
call mld_precset(P,mld_coarse_mat_,'DIST',info)
call mld_precset(P,mld_coarse_solve_,'MUMPS',info)
end select
! build the preconditioner
call psb_barrier(ictxt)
t1 = psb_wtime()
call mld_precbld(A,desc_A,P,info)
tprec = psb_wtime()-t1
call psb_amx(ictxt, tprec)
if (info /= psb_success_) then
call psb_errpush(psb_err_from_subroutine_,name,a_err='psb_precbld')
goto 9999
end if
! set the solver parameters and the initial guess
call psb_geall(x,desc_A,info)
call x%set(szero)
call psb_geasb(x,desc_A,info)
! solve Ax=b with preconditioned BiCGSTAB
call psb_barrier(ictxt)
t1 = psb_wtime()
call psb_krylov('BICGSTAB',A,P,b,x,tol,desc_A,info,itmax,iter,err,itrace=1,istop=2)
t2 = psb_wtime() - t1
call psb_amx(ictxt,t2)
call psb_geall(r,desc_A,info)
call r%set(szero)
call psb_geasb(r,desc_A,info)
call psb_geaxpby(sone,b,szero,r,desc_A,info)
call psb_spmm(-sone,A,x,sone,r,desc_A,info)
resmx = psb_genrm2(r,desc_A,info)
resmxp = psb_geamax(r,desc_A,info)
amatsize = a%sizeof()
descsize = desc_a%sizeof()
precsize = p%sizeof()
call psb_sum(ictxt,amatsize)
call psb_sum(ictxt,descsize)
call psb_sum(ictxt,precsize)
call mld_precdescr(P,info)
if (iam == psb_root_) then
write(*,'(" ")')
write(*,'("Matrix from PDE example")')
write(*,'("Computed solution on ",i8," processors")')np
write(*,'("Iterations to convergence : ",i6)')iter
write(*,'("Error estimate on exit : ",es12.5)')err
write(*,'("Time to build prec. : ",es12.5)')tprec
write(*,'("Time to solve system : ",es12.5)')t2
write(*,'("Time per iteration : ",es12.5)')t2/(iter)
write(*,'("Total time : ",es12.5)')t2+tprec
write(*,'("Residual 2-norm : ",es12.5)')resmx
write(*,'("Residual inf-norm : ",es12.5)')resmxp
write(*,'("Total memory occupation for A : ",i12)')amatsize
write(*,'("Total memory occupation for DESC_A : ",i12)')descsize
write(*,'("Total memory occupation for PREC : ",i12)')precsize
end if
call psb_gefree(b, desc_A,info)
call psb_gefree(x, desc_A,info)
call psb_spfree(A, desc_A,info)
call mld_precfree(P,info)
call psb_cdfree(desc_A,info)
call psb_exit(ictxt)
stop
9999 continue
call psb_error(ictxt)
contains
!
! get parameters from standard input
!
subroutine get_parms(ictxt,choice,idim,itmax,tol)
use psb_base_mod
implicit none
integer :: choice, idim, ictxt, itmax
real(psb_spk_) :: tol
integer :: iam, np
call psb_info(ictxt,iam,np)
if (iam == psb_root_) then
! read input parameters
call read_data(choice,5)
call read_data(idim,5)
call read_data(itmax,5)
call read_data(tol,5)
end if
call psb_bcast(ictxt,choice)
call psb_bcast(ictxt,idim)
call psb_bcast(ictxt,itmax)
call psb_bcast(ictxt,tol)
end subroutine get_parms
end program mld_sexample_ml