[MBDyn-users] Python interface

Pierangelo Masarati pierangelo.masarati at polimi.it
Sat Sep 16 08:54:59 CEST 2017


Hello.  I presume you're using the latest version of MBDyn, since you 
don't mention it.  I just checked and the example runs fine in Linux.

I'm puzzled by the fact that communication seems to occur fine for a few 
iterations (3 steps, 5 iterations each), and then fails.  I notice that 
values are inconsistent, though: a meaningless value for x, and zero for 
x' and x''.  Here is what you should expect:

i= 0  x= 0.01  xp= 1.0 xpp= 0.0
i= 1  x= 0.00869888029453  xp= 0.739776058906 xpp= 0.0
i= 2  x= 0.00890904742441  xp= 0.781809484882 xpp= -52.0447882187
i= 3  x= 0.00887509956988  xp= 0.775019913977 xpp= -43.6381030236
i= 4  x= 0.00888058309544  xp= 0.776116619087 xpp= -44.9960172046
i= 0  x= 0.0155187894123  xp= 0.551878941234 xpp= -44.8121058766
i= 1  x= 0.0137659717107  xp= 0.21533794252 xpp= -89.6242117532
i= 2  x= 0.0140684062224  xp= 0.273405368758 xpp= -68.2008402233
i= 3  x= 0.0140162235945  xp= 0.263386304208 xpp= -57.0518943855
i= 4  x= 0.0140252272847  xp= 0.265115012728 xpp= -58.9755547792
i= 0  x= 0.0145099412742  xp= -0.174540443703 xpp= -58.7009114795
i= 1  x= 0.0138427692281  xp= -0.302637476567 xpp= -80.3205421509
i= 2  x= 0.0139578843663  xp= -0.280535370032 xpp= -55.0896122011
i= 3  x= 0.0139380221806  xp= -0.284348909677 xpp= -50.8460077463
i= 4  x= 0.01394144924  xp= -0.283690914268 xpp= -51.5782073582
i= 0  x= 0.00827989978698  xp= -0.84697286754 xpp= -51.4736703422
i= 1  x= 0.00931871817262  xp= -0.647519737497 xpp= -46.9484992005
i= 2  x= 0.00913947846568  xp= -0.68193376123 xpp= -22.0443591974
i= 3  x= 0.00917040482681  xp= -0.675995899893 xpp= -28.6518517541
i= 4  x= 0.00916506873343  xp= -0.677020429821 xpp= -27.5117823773
...

Apparently, there's something weird broken in the underlying 
communication library's build that is OSX-specific.

Unfortunately we don't use that platform, so I'm afraid we won't be able 
to help much.

Sincerely, p.


On 08/29/2017 03:57 PM, Franco Lovato wrote:
>
> 	
> Questo mittente non ha superato i nostri controlli per il rilevamento di frodi e potrebbe non essere chi sembra essere. Altre informazioni sullo 
> spoofing <http://aka.ms/LearnAboutSpoofing>
> 	Commenti e suggerimenti <http://aka.ms/SafetyTipsFeedback>
>
> Hello everybody
>
> I am currently using MBDyn on OSX environment, and I'd like to use the 
> python interface. I was able to configure it and correctly install it, 
> at least apparently; however the communication seems not to work. I 
> tried to execute the example "springmass", found on MBDyn website, but 
> it seems that MBDyn is not receiving informations from the python 
> script. Here is the output:
>
>
> i= 0  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 1  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 2  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 3  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 4  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 0  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 1  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 2  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 3  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 4  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 0  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 1  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 2  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 3  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> i= 4  x= 8.02989130579e+283  xp= 0.0 xpp= 0.0
>
> send(48) nodes failed (-1)
>
>
> And then it stops. The output.txt and output.log files seem to give no 
> further information. The paths should be correctly set, so I am not 
> able to find the problem. Any suggestion will be appreciated.
>
>
> Thanks
>
> Franco
>
>
>
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> MBDyn-users at mbdyn.org
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-- 
Pierangelo Masarati
Professor
Dipartimento di Scienze e Tecnologie Aerospaziali
Politecnico di Milano

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