[Nek5000-users] Problem using genmap with large numbers of elements

[nek5000-users at lists.mcs.anl.gov]

I looked at the genmap issue, and I am quite sure that the fix is to 
simply comment out the lines

c         if(nelt.ge.1000000.and.cbl(f,e).eq.'P  ')
c     $     call copyi4(bl(1,f,e),buf(5),1) !Integer ...

as suggested also in the pdf on github, 
https://github.com/Nek5000/Nek5000/issues/125. The reason is that 
buf(5),buf(6) contain the element number as a real*8, so no conversion 
is needed. Therefore, all went ok up to about 2.5M elements, because 
then 4 bytes were sufficient to store the float.
The corresponding lines for wdsizi=4 should remain, though.

Philipp




On 2016-12-22 21:36, nek5000-users at lists.mcs.anl.gov wrote:
>
> OK... I see that genmap is indeed wdsize=8...  never mind...
>
> ________________________________________
> From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
> Sent: Thursday, December 22, 2016 2:32 PM
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Problem using genmap with large numbers of elements
>
> I usually run genmap in 64 bit precision ---
>
> To me, it looks like maketools does not build it this way ?  (Or am I mis-reading the script?)
>
> I'm looking at tools/genmap/makefile ...
>
> genmap can be built with -r8
>
> I'm not certain about the other tools.   Certainly n2to3 could be build with -r8
>
> Paul
>
> ________________________________________
> From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
> Sent: Thursday, December 22, 2016 7:52 AM
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Problem using genmap with large numbers of elements
>
> Yes, this bug is reported here https://github.com/Nek5000/Nek5000/issues/125 but has not been resolved yet.
> Stefan
>
>
> -----Original message-----
>> From:nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
>> Sent: Thursday 22nd December 2016 0:23
>> To: nek5000-users at lists.mcs.anl.gov
>> Subject: Re: [Nek5000-users] Problem using genmap with large numbers of elements
>>
>>
>> Dear Ricardo,
>>
>> I believe there is a fix to this... I'm not 100% certain of the status in the repo.
>>
>> Perhaps one of the other developers is aware...
>>
>> Will try to find out more.
>>
>> Best, Paul
>>
>> ________________________________________
>> From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
>> Sent: Wednesday, December 21, 2016 3:21 PM
>> To: nek5000-users at lists.mcs.anl.gov
>> Subject: [Nek5000-users] Problem using genmap with large numbers of elements
>>
>> Dear Nek Users,
>> We are about to set up a new case with about 29692 in 2D, which we
>> would like to extrude to about 150 elements in 3D, giving a total of
>> about 30k times 150 = 4.5M elements. n2to3 works fine, but genmap
>> gives a "periodic mismatch error". Having a lower number of extrusion
>> elements, say 30k times 70 = 2.1M elements, works fine. Changing the
>> tolerance in genmap does not fix it.
>>
>> Before diving into the code of n2to3 and genmap, we wanted to ask
>> whether somebody has experienced that before, and whether you'd know a
>> potential fix for the problem.
>>
>> We used both an older version of genmap and the latest github version.
>>
>> Thanks a lot!
>> Ricardo
>>
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