psblas3/test/pargen/psb_s_pde2d.f90

!    
!                Parallel Sparse BLAS  version 3.5
!      (C) Copyright 2006, 2010, 2015, 2017
!        Salvatore Filippone    Cranfield University
!        Alfredo Buttari        CNRS-IRIT, Toulouse
!   
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!    modification, are permitted provided that the following conditions
!    are met:
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!   
!    
! File: psb_s_pde2d.f90
!
! Program: psb_s_pde2d
! This sample program solves a linear system obtained by discretizing a
! PDE with Dirichlet BCs. 
! 
!
! The PDE is a general second order equation in 2d
!
!   a1 dd(u)  a2 dd(u)   b1 d(u)   b2 d(u) 
! -   ------ -  ------   -----  +  ------  + c u = f
!      dxdx     dydy        dx       dy    
!
! with Dirichlet boundary conditions
!   u = g 
!
!  on the unit square  0<=x,y<=1.
!
!
! Note that if b1=b2=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 psb_s_pde2d_mod
contains
  !
  ! functions parametrizing the differential equation 
  !  
  function b1(x,y)
    use psb_base_mod, only : psb_spk_
    real(psb_spk_) :: b1
    real(psb_spk_), intent(in) :: x,y
    b1=1.e0/sqrt(2.e0)
  end function b1
  function b2(x,y)
    use psb_base_mod, only : psb_spk_
    real(psb_spk_) ::  b2
    real(psb_spk_), intent(in) :: x,y
    b2=1.e0/sqrt(2.e0)
  end function b2
  function c(x,y)
    use psb_base_mod, only : psb_spk_
    real(psb_spk_) ::  c
    real(psb_spk_), intent(in) :: x,y
    c=0.e0
  end function c
  function a1(x,y)
    use psb_base_mod, only : psb_spk_
    real(psb_spk_) ::  a1   
    real(psb_spk_), intent(in) :: x,y
    a1=1.e0/80
  end function a1
  function a2(x,y)
    use psb_base_mod, only : psb_spk_
    real(psb_spk_) ::  a2
    real(psb_spk_), intent(in) :: x,y
    a2=1.e0/80
  end function a2
  function g(x,y)
    use psb_base_mod, only : psb_spk_, sone, szero
    real(psb_spk_) ::  g
    real(psb_spk_), intent(in) :: x,y
    g = szero
    if (x == sone) then
      g = sone
    else if (x == szero) then 
      g = exp(-y**2)
    end if
  end function g

end module psb_s_pde2d_mod

program psb_s_pde2d
  use psb_base_mod
  use psb_prec_mod
  use psb_krylov_mod
  use psb_util_mod
  use psb_s_pde2d_mod
  implicit none

  ! input parameters
  character(len=20) :: kmethd, ptype
  character(len=5)  :: afmt
  integer(psb_ipk_) :: idim

  ! miscellaneous 
  real(psb_spk_), parameter :: one = 1.e0
  real(psb_dpk_) :: t1, t2, tprec 

  ! sparse matrix and preconditioner
  type(psb_sspmat_type) :: a
  type(psb_sprec_type)  :: prec
  ! descriptor
  type(psb_desc_type)   :: desc_a
  ! dense vectors
  type(psb_s_vect_type) :: xxv,bv
  ! parallel environment
  integer(psb_ipk_) :: ictxt, iam, np

  ! solver parameters
  integer(psb_ipk_) :: iter, itmax,itrace, istopc, irst
  integer(psb_long_int_k_) :: amatsize, precsize, descsize, d2size
  real(psb_spk_)   :: err, eps

  ! other variables
  integer(psb_ipk_) :: info, i
  character(len=20) :: name,ch_err
  character(len=40) :: fname

  info=psb_success_


  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
  if(psb_get_errstatus() /= 0) goto 9999
  name='pde2d90'
  call psb_set_errverbosity(itwo)
  !
  ! Hello world
  !
  if (iam == psb_root_) then 
    write(*,*) 'Welcome to PSBLAS version: ',psb_version_string_
    write(*,*) 'This is the ',trim(name),' sample program'
  end if
  !
  !  get parameters
  !
  call get_parms(ictxt,kmethd,ptype,afmt,idim,istopc,itmax,itrace,irst)

  !
  !  allocate and fill in the coefficient matrix, rhs and initial guess 
  !
  call psb_barrier(ictxt)
  t1 = psb_wtime()
  call psb_gen_pde2d(ictxt,idim,a,bv,xxv,desc_a,afmt,a1,a2,b1,b2,c,g,info)  
  call psb_barrier(ictxt)
  t2 = psb_wtime() - t1
  if(info /= psb_success_) then
    info=psb_err_from_subroutine_
    ch_err='psb_gen_pde2d'
    call psb_errpush(info,name,a_err=ch_err)
    goto 9999
  end if
  if (iam == psb_root_) write(psb_out_unit,'("Overall matrix creation time : ",es12.5)')t2
  if (iam == psb_root_) write(psb_out_unit,'(" ")')
  !
  !  prepare the preconditioner.
  !  
  if(iam == psb_root_) write(psb_out_unit,'("Setting preconditioner to : ",a)')ptype
  call prec%init(ptype,info)

  call psb_barrier(ictxt)
  t1 = psb_wtime()
  call prec%build(a,desc_a,info)
  if(info /= psb_success_) then
    info=psb_err_from_subroutine_
    ch_err='psb_precbld'
    call psb_errpush(info,name,a_err=ch_err)
    goto 9999
  end if

  tprec = psb_wtime()-t1

  call psb_amx(ictxt,tprec)

  if (iam == psb_root_) write(psb_out_unit,'("Preconditioner time : ",es12.5)')tprec
  if (iam == psb_root_) write(psb_out_unit,'(" ")')
  call prec%descr()
  !
  ! iterative method parameters 
  !
  if(iam == psb_root_) write(psb_out_unit,'("Calling iterative method ",a)')kmethd
  call psb_barrier(ictxt)
  t1 = psb_wtime()  
  eps   = 1.d-9
  call psb_krylov(kmethd,a,prec,bv,xxv,eps,desc_a,info,& 
       & itmax=itmax,iter=iter,err=err,itrace=itrace,istop=istopc,irst=irst)     

  if(info /= psb_success_) then
    info=psb_err_from_subroutine_
    ch_err='solver routine'
    call psb_errpush(info,name,a_err=ch_err)
    goto 9999
  end if

  call psb_barrier(ictxt)
  t2 = psb_wtime() - t1
  call psb_amx(ictxt,t2)
  amatsize = a%sizeof()
  descsize = desc_a%sizeof()
  precsize = prec%sizeof()
  call psb_sum(ictxt,amatsize)
  call psb_sum(ictxt,descsize)
  call psb_sum(ictxt,precsize)

  if (iam == psb_root_) then
    write(psb_out_unit,'(" ")')
    write(psb_out_unit,'("Time to solve system          : ",es12.5)')t2
    write(psb_out_unit,'("Time per iteration            : ",es12.5)')t2/iter
    write(psb_out_unit,'("Number of iterations          : ",i0)')iter
    write(psb_out_unit,'("Convergence indicator on exit : ",es12.5)')err
    write(psb_out_unit,'("Info  on exit                 : ",i0)')info
    write(psb_out_unit,'("Total memory occupation for A:      ",i12)')amatsize
    write(psb_out_unit,'("Total memory occupation for PREC:   ",i12)')precsize    
    write(psb_out_unit,'("Total memory occupation for DESC_A: ",i12)')descsize
    write(psb_out_unit,'("Storage type for DESC_A: ",a)') desc_a%get_fmt()
  end if


  !  
  !  cleanup storage and exit
  !
  call psb_gefree(bv,desc_a,info)
  call psb_gefree(xxv,desc_a,info)
  call psb_spfree(a,desc_a,info)
  call prec%free(info)
  call psb_cdfree(desc_a,info)
  if(info /= psb_success_) then
    info=psb_err_from_subroutine_
    ch_err='free routine'
    call psb_errpush(info,name,a_err=ch_err)
    goto 9999
  end if

  call psb_exit(ictxt)
  stop

9999 call psb_error(ictxt)

  stop

contains
  !
  ! get iteration parameters from standard input
  !
  subroutine  get_parms(ictxt,kmethd,ptype,afmt,idim,istopc,itmax,itrace,irst)
    integer(psb_ipk_) :: ictxt
    character(len=*) :: kmethd, ptype, afmt
    integer(psb_ipk_) :: idim, istopc,itmax,itrace,irst
    integer(psb_ipk_) :: np, iam
    integer(psb_ipk_) :: ip

    call psb_info(ictxt, iam, np)

    if (iam == 0) then
      read(psb_inp_unit,*) ip
      if (ip >= 3) then
        read(psb_inp_unit,*) kmethd
        read(psb_inp_unit,*) ptype
        read(psb_inp_unit,*) afmt

        read(psb_inp_unit,*) idim
        if (ip >= 4) then
          read(psb_inp_unit,*) istopc
        else
          istopc=1        
        endif
        if (ip >= 5) then
          read(psb_inp_unit,*) itmax
        else
          itmax=500
        endif
        if (ip >= 6) then
          read(psb_inp_unit,*) itrace
        else
          itrace=-1
        endif
        if (ip >= 7) then
          read(psb_inp_unit,*) irst
        else
          irst=1
        endif

        write(psb_out_unit,'("Solving matrix       : ell1")')      
        write(psb_out_unit,'("Grid dimensions      : ",i5," x ",i5)')idim,idim
        write(psb_out_unit,'("Number of processors : ",i0)')np
        write(psb_out_unit,'("Data distribution    : BLOCK")')
        write(psb_out_unit,'("Preconditioner       : ",a)') ptype
        write(psb_out_unit,'("Iterative method     : ",a)') kmethd
        write(psb_out_unit,'(" ")')
      else
        ! wrong number of parameter, print an error message and exit
        call pr_usage(izero)      
        call psb_abort(ictxt)
        stop 1
      endif
    end if
    ! broadcast parameters to all processors
    call psb_bcast(ictxt,kmethd)
    call psb_bcast(ictxt,afmt)
    call psb_bcast(ictxt,ptype)
    call psb_bcast(ictxt,idim)
    call psb_bcast(ictxt,istopc)
    call psb_bcast(ictxt,itmax)
    call psb_bcast(ictxt,itrace)
    call psb_bcast(ictxt,irst)


    return

  end subroutine get_parms
  !
  !  print an error message 
  !  
  subroutine pr_usage(iout)
    integer(psb_ipk_) :: iout
    write(iout,*)'incorrect parameter(s) found'
    write(iout,*)' usage:  pde2d90 methd prec dim &
         &[istop itmax itrace]'  
    write(iout,*)' where:'
    write(iout,*)'     methd:    cgstab cgs rgmres bicgstabl' 
    write(iout,*)'     prec :    bjac diag none'
    write(iout,*)'     dim       number of points along each axis'
    write(iout,*)'               the size of the resulting linear '
    write(iout,*)'               system is dim**3'
    write(iout,*)'     istop     stopping criterion  1, 2  '
    write(iout,*)'     itmax     maximum number of iterations [500] '
    write(iout,*)'     itrace    <=0  (no tracing, default) or '  
    write(iout,*)'               >= 1 do tracing every itrace'
    write(iout,*)'               iterations ' 
  end subroutine pr_usage

end program psb_s_pde2d