[Nek5000-users] Reading binary data
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Tue Aug 17 11:40:06 CDT 2010
Paul,
That info did the trick -- Thanks!!
--Mike
On Aug 13, 2010, at 3:28 PM, <nek5000-users at lists.mcs.anl.gov> <nek5000-users at lists.mcs.anl.gov> wrote:
>
> Hi Mike,
>
> I was able to track this down by
>
> cd nek5_svn/trunk/nek
>
> edit prepost.f
>
> search for ifxyo
>
> Near one of these I find:
>
> call mfo_outv(xm1,ym1,zm1,nout,nxo,nyo,nzo)
>
>
> and looking at the mfo_outv() [ multifile-output,
> output a vector ] routine, I find:
>
>
> j = 0
> if (wdsizo.eq.4) then ! 32-bit output
> do iel = 1,nel
> call copyx4 (u4(j+1),u(1,iel),nxyz)
> j = j + nxyz
> call copyx4 (u4(j+1),v(1,iel),nxyz)
> j = j + nxyz
> if(if3d) then
> call copyx4 (u4(j+1),w(1,iel),nxyz)
> j = j + nxyz
>
>
> which indicates that the vector fields are output a
>
> vx(:,:,:,1) nxyz points (32 bits/pt)
> vy(:,:,:,1) nxyz points
> vz(:,:,:,1) nxyz points
> vx(:,:,:,2) nxyz points
> vy(:,:,:,2) nxyz points
> vz(:,:,:,2) nxyz points
> :
> vx(:,:,:,nel) nxyz points
> vy(:,:,:,nel) nxyz points
> vz(:,:,:,nel) nxyz points
>
> etc.
>
> So, you would likely see,
>
> xyz (interleaved, as above)
> uvw (interleaved, as above)
> p (entire field)
> T (entire field)
> PS1 (entire field)
> PS2 (entire field)
>
> etc.
>
> Note that the order of the elements will likely not be
> sequential unless you are running on one processor. It
> will instead be ordered according to the header info.
>
> Paul
>
>
>
>
>
>
> On Fri, 13 Aug 2010, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Stefan,
>>
>> I'm still having some problems reading the field data properly. So, please consider a field file that has BOTH mesh data and field data, and assume there are three fields stored (u,v,w,p).
>>
>> After the initial file data (header: 132 bytes, endian 4 bytes, mapping: nel* 4 bytes), does the mesh data come in single chunk before field data (as discussed in your message below):
>>
>> LOOP over all elements
>> LOOP i = {x,y,z}
>> i for all GLL points (internal element points)
>> ENDLOOP
>> ENDLOOP
>>
>> If that is indeed all before the field data, is the field data then organized as
>>
>> LOOP over all elements
>> LOOP i = three fields
>> i for all GLL points (internal element points)
>> ENDLOOP
>> ENDLOOP
>>
>> or, is it
>>
>> LOOP over all elements
>> LOOP i = GLL points
>> i for all fields
>> ENDLOOP
>> ENDLOOP
>>
>> ??
>>
>> Is there by chance a detailed description for the format of the field file somewhere that I am missing?
>>
>> --Mike
>>
>> On Aug 11, 2010, at 3:50 PM, <nek5000-users at lists.mcs.anl.gov> <nek5000-users at lists.mcs.anl.gov> wrote:
>>
>>> Hi Mike,
>>>
>>> vector fields (e.g. mesh coordinates) are stored in the following way:
>>>
>>> LOOP over all elements
>>> LOOP i = {x,y,z}
>>> i for all GLL points (internal element points)
>>> ENDLOOP
>>> ENDLOOP
>>>
>>> 2D example with (E=2,N=2):
>>> x1_1 x2_1 x3_1 y1_1 y2_1 y3_1 x1_1 x2_2 x3_2 y1_2 y2_2 y3_2
>>>
>>> where x2_1 means the x-coordinate of the 2nd GLL point of element 1.
>>>
>>> hth,
>>> Stefan
>>>
>>> On Aug 11, 2010, at 11:34 PM, <nek5000-users at lists.mcs.anl.gov> wrote:
>>>
>>>>
>>>> Hello All. I found this helpful message from Stefan regarding the structure of a binary field file. Could someone please tell me what the structure is when the geometry info is also contained?
>>>>
>>>> Thanks!
>>>> --Mike
>>>>
>>>> nek5000-users at lists.mcs.anl.gov nek5000-users at lists.mcs.anl.gov
>>>>> Thu May 6 07:18:03 CDT 2010
>>>>> • Previous message: [Nek5000-users] Reading binary data
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>>>>> Hi Fred,
>>>>>
>>>>> header: 132 bytes
>>>>> endian test tag: 4 bytes
>>>>> element mapping: nel* 4 bytes
>>>>> data: nfields*nxyz*nel* wdsizo (where wdsizo is 4 or 8 bytes)
>>>>> metadata (min/max values): nfields*2*nel * 4 bytes
>>>>>
>>>>> Stefan
>>>>>
>>>>
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