[petsc-users] local row calculation in 3D

[Randall Mackie]

You are right! I just didn't read all the way to the end of your email.
Sorry about that.
So here is a little more code that does it correctly:

      PetscInt, pointer :: ltog(:)

      call DAGetGlobalIndicesF90(da,nloc,ltog,ierr); CHKERRQ(ierr)

      do kk=zs,zs+zm-1
        do jj=ys,ys+ym-1
          do ii=xs,xs+xm-1

            row=ii-gxs + (jj-gys)*gxm + (kk-gzs)*gxm*gym
            grow=ltog(3*row + 1)

[all your code here]

              call MatSetValues(A,i1,grow,ic,col,v,INSERT_VALUES,
     .             ierr); CHKERRQ(ierr)

[more code here]

      call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr)
      call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr); CHKERRQ(ierr)



Hope this is a little more helpful. As Jed points out, there are other ways
to do the same
thing (and probably more efficiently than what I've outlined here).

Randy M.


On Tue, Apr 19, 2011 at 12:00 AM, ilyas ilyas <ilyascfd at gmail.com> wrote:

> Hi Randy,
>
> Thank you for your answer.
>
> I have already done it. You can see it in my first e-mail.
>
> It does not work properly for all number of processors.
> For certain number of processors, it works correctly,
> not for all number of processors.
> For example, for 1,2,or 3 processors, it's ok.
> For 4 processors, it gives wrong location, so on.
> "Problem" occurs in 3rd dimension ( (kk-gzs)*gxm*gym )
>
> Here is another suggestion (I have not tried yet) ;
>
>        do kk=zs,zs+zm-1
>         do jj=ys,ys+ym-1
>           do ii=xs,xs+xm-1
>
>             row=ii-gxs + (jj-gys)*MX + (kk-gzs)*MX*MY
>
> MX,MY,MZ are global dimensions.This is also what I do serially
>
> Do you think that it is correct or any other suggestions?
>
> Regards,
> Ilyas.
>
> 2011/4/18 Randall Mackie <rlmackie862 at gmail.com>
>
>> Here's how I do it:
>>
>>        do kk=zs,zs+zm-1
>>         do jj=ys,ys+ym-1
>>           do ii=xs,xs+xm-1
>>
>>              row=ii-gxs + (jj-gys)*gxm + (kk-gzs)*gxm*gym
>>
>>
>> Good luck,
>>
>> Randy M.
>>
>>
>>
>> On Mon, Apr 18, 2011 at 6:54 AM, ilyas ilyas <ilyascfd at gmail.com> wrote:
>>
>>> Hi,
>>> Thank you for your suggestion. I will take it into account.
>>> Since changing this structure in my "massive" code may take  too much
>>> time,
>>> I would like to know that how "row" is calculated in 3D, independently
>>> from processor numbers.
>>>
>>> Regards,
>>> Ilyas
>>>
>>> 2011/4/18 Matthew Knepley <knepley at gmail.com>
>>>
>>>> On Mon, Apr 18, 2011 at 8:34 AM, ilyas ilyas <ilyascfd at gmail.com>wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> In ex14f.F in KSP, "row" variable is calculated either
>>>>>
>>>>
>>>> These are very old. I suggest you use the FormFunctionLocal() approach
>>>> in ex5f.F which
>>>> does not calculate global row numbers when using a DA.
>>>>
>>>>    Matt
>>>>
>>>>
>>>>> 349: do 30 j=ys,ys+ym-1
>>>>> 350: ...
>>>>> 351: do 40 i=xs,xs+xm-1
>>>>> 352:          row = i - gxs + (j - gys)*gxm + 1
>>>>>
>>>>> or
>>>>>
>>>>> 442: do 50 j=ys,ys+ym-1
>>>>> 443: ...
>>>>> 444: row = (j - gys)*gxm + xs - gxs
>>>>> 445: do 60 i=xs,xs+xm-1
>>>>> 446:          row = row + 1
>>>>>
>>>>> How can I calculate "row" in 3D ?
>>>>>
>>>>> I tried this;
>>>>>
>>>>> do k=zs,zs+zm-1
>>>>>    do j=ys,ys+ym-1
>>>>>       do i=xs,xs+xm-1
>>>>>
>>>>>            row = i - gxs + (j - gys)*gxm + (k - gzs)*gxm*gym + 1
>>>>>
>>>>> It does not work for certain number of processors.
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Ilyas
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> What most experimenters take for granted before they begin their
>>>> experiments is infinitely more interesting than any results to which their
>>>> experiments lead.
>>>> -- Norbert Wiener
>>>>
>>>
>>>
>>
>
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