NVIDIA-GPU-Bootcamp-Training/hpc/openacc/English/Fortran/source_code/lab2/jacobi.f90

! Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
!
! Redistribution and use in source and binary forms, with or without
! modification, are permitted provided that the following conditions
! are met:
!  * Redistributions of source code must retain the above copyright
!    notice, this list of conditions and the following disclaimer.
!  * 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.
!  * Neither the name of NVIDIA CORPORATION nor the names of its
!    contributors may be used to endorse or promote products derived
!    from this software without specific prior written permission.
!
! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``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 COPYRIGHT OWNER OR
! 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.

program jacobi
  use laplace2d
  implicit none
  integer, parameter :: fp_kind=kind(1.0d0)
  integer, parameter :: n=4096, m=4096, iter_max=1000
  integer :: i, j, iter
  real(fp_kind), dimension (:,:), allocatable :: A, Anew
  real(fp_kind) :: tol=1.0e-6_fp_kind, error=1.0_fp_kind
  real(fp_kind) :: start_time, stop_time

  call initialize(A, Anew, m, n)
   
  write(*,'(a,i5,a,i5,a)') 'Jacobi relaxation Calculation:', n, ' x', m, ' mesh'
 
  call cpu_time(start_time) 

  iter=0
  
  do while ( error .gt. tol .and. iter .lt. iter_max )

    error = calcNext(A, Anew, m, n)
    call swap(A, Anew, m, n)

    if(mod(iter,100).eq.0 ) write(*,'(i5,f10.6)'), iter, error

    iter = iter + 1

  end do

  call cpu_time(stop_time) 
  write(*,'(a,f10.3,a)')  ' completed in ', stop_time-start_time, ' seconds'

  deallocate (A,Anew)
end program jacobi