[Nek5000-users] Reading binary data
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Thu Aug 12 02:06:45 CDT 2010
The 12288 bytes is the metadata for all 3 mesh coordinates:
ndim * nel * 2 * 4 bytes
Stefan
On Aug 12, 2010, at 12:21 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
> Sorry -- I'm still not getting it.
>
> The first file had mesh coordinates and field information in it; here is what the header shows:
>
> #std 4 8 8 8 512 512 0.2000000000000E+02 1000 0 1 XUPS02
>
> The size of this file is 9476232, but I can't figure out what is contributing to that size. For the next field file, the header shows:
>
> #std 4 8 8 8 512 512 0.1200000000000E+03 6000 0 1 UPS02
>
> The size of this file is 6318216, which is exactly predicted by the expression below -- all is well.
>
> What is the makeup of the 3158016 bytes difference between these files? The mesh coordinates alone are only
>
> 512 * 8^3 * 4 * 3 (ndim) = 3145728 bytes
>
> Where and what are the remaining 12288 bytes?
>
> Thanks.
>
>
>
> On Aug 11, 2010, at 4:09 PM, <nek5000-users at lists.mcs.anl.gov> wrote:
>
>> No, if a field file only contains the geometry (mesh coordinates) nfields is equal to ndim (2 or 3).
>> Stefan
>>
>>
>> On Aug 12, 2010, at 12:01 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
>>
>>> Stefan,
>>>
>>> Thanks. I figured that, but the binary file size doesn't seem to be adding up. For example, a field file that doesn't have geometry data is the size described by the initial thread, i.e.
>>>
>>> 132 bytes + 4 bytes + nel* 4 bytes + nfields*nxyz*nel* wdsizo + nfields*2*nel * 4 bytes
>>>
>>> My naive assumption was that a field file with xyz data would then have the additional space requirement of
>>>
>>> nx*ny*nz*nel*wdsizo
>>>
>>> but the file's bigger than that. What info am I missing?
>>>
>>> --Mike
>>>
>>> On Aug 11, 2010, at 3:50 PM, <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
>>>>>> • Next message: [Nek5000-users] History points
>>>>>> • Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
>>>>>> 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
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Nek5000-users mailing list
>>>>> Nek5000-users at lists.mcs.anl.gov
>>>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>>
>>>> _______________________________________________
>>>> Nek5000-users mailing list
>>>> Nek5000-users at lists.mcs.anl.gov
>>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>
>>> _______________________________________________
>>> Nek5000-users mailing list
>>> Nek5000-users at lists.mcs.anl.gov
>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>
>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>
> _______________________________________________
> Nek5000-users mailing list
> Nek5000-users at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
More information about the Nek5000-users
mailing list