[MBDyn-users] Output time period in *.log -> work around using an abstract node

Rix, Patrick Patrick.Rix at repower.de
Thu Feb 17 09:35:56 CET 2011


Hello Jens,
(hi Pierangelo)

I'm not sure if this helps, but in the meantime until Pierangelo has added an additional column with a "written time step marker"-flag to the *.out file (..I missed that, too) you can try to capture the simulation time in an abstract node whose output would contain only the time values of those steps triggered by the outputmeter.It's a little bit clumsy that way, but that's how we solved this problem. Well at least it's working and it should even work when using variable time step strategy for the simulation.
I attached a zip file with an example. The desired time output should appear in the *.abs file in the 2nd column of abstract node 11.

Reducing the output right at run time and afterwards via post-processing was something I worked on for a while some time ago (to get rid of dealing with huge text files). I also investigated into MBdynText-to-NetCDF conversion and wrote some tools giving quite good results: reduction in file size by factor ~4 for MBDynText-to-NetCDFfloat conversion (converting from floats to 2byte-ints finally would result in approx. 8 times less compared to text format); if you are interested I can send you a test-version.

@Pierangelo:
 I'd like to add another wish to the list apart from having a "written time step marker"-flag:
  --> would it be possible (with acceptable effort) to add a switch to control the number format for binary NetCDF-output, allowing to choose between  DOUBLE and  FLOAT ?

Best regards,
Patrick.


-----Ursprüngliche Nachricht-----
Von: mbdyn-users-bounces at mbdyn.org [mailto:mbdyn-users-bounces at mbdyn.org] Im Auftrag von Jens.vanSchelve at Emerson.com
Gesendet: Mittwoch, 16. Februar 2011 16:59
An: mbdyn-users at mbdyn.org
Betreff: Re: [MBDyn-users] Output time period in *.log


Giuseppe: The *.out file stores information of EVERY timestep ignoring if the data is passed to the output (*.mov, *.jnt...) files. So if the simulation itself starts a second x its ok, but not if only the output starts at second x.

Pierangelo: So it would not be possible, too complicated or conflict other softwares to add something like "output time: <starttime> <endtime>" to the *.log file? -> Considering the fact that "output frequency: <frequency>" is already there? Or do you think of some other special cases, because of the generec drive caller, that there might be several start- and end times? Which would also make the standart output files even harder to read.

I was also considering the NetCDF output already, but our current mbdyn post-processor is based on the standart output files and am not quite sure if I find time to implement a MBDyn-NetCDF parser, however I already looked into some NetCDF c++ examples and at some point in the future I will do this. Having the start and end time of the output in the output files somewhere would just be much quicker to implement for now :) It is still not that critical and was just meant to reduce the amount of output.

Jens

-----Ursprüngliche Nachricht-----
Von: mbdyn-users-bounces at mbdyn.org [mailto:mbdyn-users-bounces at mbdyn.org] Im Auftrag von Pierangelo Masarati
Gesendet: Mittwoch, 16. Februar 2011 15:23
An: van Schelve, Jens [INDAUTO/SSB/SAL]
Cc: mbdyn-users at mbdyn.org
Betreff: Re: [MBDyn-users] Output time period in *.log

Jens.vanSchelve at Emerson.com wrote:
>
> Hi,
>
> Why does only the output frequency appear in the *.log file but NOT
> start and end time of the output?

Because that field in the log file was defined well before the output meter became available.

> Or is this information stored somewhere else in the output files and I
> just have overlooked it?

No.

> Would be nice to have this information for post-processing. Ok, one
> could parse the input file, but thats not very elegant.
>
> Example: By using the output meter one can define start time, end time
> and time steps of the mbdyn output. E.g.
> output meter: meter, 10., forever, steps, 2; Which will write only
> output (*.mov, *.jnt...) for every second time step starting from
> time=10.

The output meter in theory allows any type of drive caller, which means that we need to define a syntax that takes this into account.  Perhaps we could log the drive caller's definition.

You could also consider using NetCDF based output (not complete, but in some cases more detailed than regular output).

Cheers, p.


-----Ursprüngliche Nachricht-----
Von: Giuseppe Quaranta [mailto:quaranta at aero.polimi.it]
Gesendet: Mittwoch, 16. Februar 2011 15:20
An: van Schelve, Jens [INDAUTO/SSB/SAL]
Betreff: Re: [MBDyn-users] Output time period in *.log

Hi Jens,

look at the *.out file. It logs a list of the time at which a computation has been performed, plus other information regarding the number of iterations etc., from the beginning to the end.

Regards,

g.
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