Fortran 子程序返回错误值 [英] Fortran subroutine returning wrong values

问题描述

嘿，我正在开发一个 Fortran 程序，但遇到了一个奇怪的问题.当我尝试在调用特定子例程之前直接输出数组的某些值时，我得到了正确的值.然后我尝试在我启动子程序时输出相同数组的一些值，它们是 0.我最终在子程序之后输出数组的值，这些值回到预期值.谁能帮我理解为什么?我的代码如下:

Hey I'm working on a fortran program and have ran across an odd problem. When I try to output some values of an array directly before calling a specific subroutine I get the correct values. I then try to output some values of the same array right as I start the subroutine, and they are 0. I finally output the values of the array after the subroutine and the values are back to the expected values. Could anyone help me understand why? My code is below:

首先，在主函数中调用子程序，我想在write语句中输出值:

First, the calling of the subroutine in the main function, with values I want outputted in the write statements:

if (iter .eq. 5) then
  write(*,*) 'vp vals: ',vp(0,23471), vp(0,23475)
end if 

CALL GRID_DIVISION( &
&            NPTMAX, DIM, TYPEMAX, NEIGHMAX, NPTC, GRIDLIMIT, &
&            GRIDN, GRIDNUM, GRID, GNEIGH, XP, PTTYPE, TYPE, &
&            GRIDP, TEMP_GRIDP, GNEIGHMAX, PAINT, VP, ITER, gridvel &
&          )

if (iter .eq. 5) then
  write(*,*) 'vp vals: ',vp(0,23471), vp(0,23475)
end if 

这是调用下面的子程序，我只贴出相关部分:

This is calling the following subroutine, of which I will post only the relevant part:

SUBROUTINE GRID_DIVISION( &
&            NPTMAX, DIM, TYPEMAX, NEIGHMAX, NPTC, GRIDLIMIT, &
&            GRIDN, GRIDNUM, GRID, GNEIGH, XP, PTTYPE, TYPE, &
&            GRIDP, TEMP_GRIDP, GNEIGHMAX, PAINT,VP,ITER, gridvel &
&          )
  IMPLICIT NONE
  INTEGER, INTENT(IN)    :: NPTMAX, DIM, TYPEMAX, NEIGHMAX, GNEIGHMAX
  INTEGER, INTENT(IN)    :: NPTC
  INTEGER, INTENT(IN)    :: GRIDLIMIT
  INTEGER, INTENT(IN)    :: GRIDN(0: DIM - 1)
  INTEGER, INTENT(IN)    :: GRIDNUM
  INTEGER, INTENT(IN)    :: PTTYPE(0: NPTMAX)
  INTEGER, INTENT(IN)    :: TYPE(0: TYPEMAX)
  INTEGER, INTENT(INOUT) :: GRIDP(0: NPTMAX)
  INTEGER, INTENT(INOUT) :: GNEIGH(1: GRIDLIMIT, 0: GNEIGHMAX)
  REAL   , INTENT(IN)    :: GRID(1: GRIDLIMIT, 0: DIM - 1, 0: 1)
  REAL   , INTENT(IN)    :: XP(0: DIM - 1, 0: NPTMAX)
  REAL   , INTENT(IN)    :: VP(0: DIM - 1, 0: NPTMAX)
  INTEGER, INTENT(INOUT) :: TEMP_GRIDP(0: NPTMAX)
  INTEGER, INTENT(INOUT) :: PAINT(0:NPTMAX)
  INTEGER, INTENT(INOUT) :: ITER
  real, intent(inout)    :: gridvel(GRIDNUM,0:1)
  INTEGER :: II, JJ, KK
  INTEGER :: DNUM
  INTEGER :: GRIDXP
  INTEGER :: SGRIDXP
  INTEGER :: EGRIDXP
  INTEGER :: SGRIDYP
  INTEGER :: EGRIDYP
  INTEGER :: SEARCH
  INTEGER :: SCOUNT
  INTEGER :: FCOUNT
  INTEGER :: ERROR
  INTEGER, PARAMETER :: CELL = 2 

  if (iter .eq. 5) then
    write(*,*) 'vp vals: ',vp(0,23471), vp(0,23475)
  end if 
...
end subroutine

本节之后还有更多未输出的内容.当我运行代码时，本节第 5 次迭代的输出是:

With more stuff after this section which is not ouputted. When I run the code my outputs on iteration 5 for this section are:

vp vals:    75.00000        75.00000
vp vals:     0.00000000E+00  0.0000000E+00
vp vals:    75.00000        75.00000

我就是想不通为什么我的数组 VP 在子程序中没有值.

I simply can't figure out why my array VP does not have values in the subroutine.

推荐答案

我想通了.VP 被分配为

I figured it out. VP was allocated as

VP(0:DIM,0:NPTMAX) 

在主程序和

VP(0:DIM-1,0:NPTMAX) 

在子程序中！这导致了错误.

in the subroutine! This caused the error.

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