Problem with cosine function

Discussion about the use of Simantics System Dynamics
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rosenm
Posts: 5
Joined: December 6th, 2014, 9:54 am

Problem with cosine function

Post by rosenm » December 6th, 2014, 10:06 am

Hello!
I am fascinated from the sysdyn tool! Big thanks to it's developers.
I am trying to simulate a simple model, spring_mass system, in which cosine function is used, please see attached file. Unfortunately, I got an error message "Simulation failed. No value for xdd". I have a feeling, that the program doesn't understand that the cosine function exist in it's list of functions.
Please help!

Regards,
Rosen MITREV, TU-Sofia, Bulgaria
Attachments
SpringMass.rar
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rosenm
Posts: 5
Joined: December 6th, 2014, 9:54 am

Re: Problem with cosine function

Post by rosenm » December 8th, 2014, 10:00 am

Problem solved!
Just switched to OpenModelicaSolver.
Tuomas Miettinen
Site Admin
Posts: 31
Joined: March 11th, 2013, 3:14 pm

Re: Problem with cosine function

Post by Tuomas Miettinen » December 8th, 2014, 10:27 am

Yup, the Internal solver in under development and thus lacking some Modelica features. In the upcoming release the Internal solver will be improved a lot and it will be better than OpenModelica in many applications.

BR,
Tuomas
rosenm
Posts: 5
Joined: December 6th, 2014, 9:54 am

Re: Problem with cosine function

Post by rosenm » December 9th, 2014, 12:21 pm

Tuomas, thanks for the answer, community is looking forward to the next version:)
Another question - is it possible to use random numbers in the sysdyn tool?
Regards,
Rosen
Tuomas Miettinen
Site Admin
Posts: 31
Joined: March 11th, 2013, 3:14 pm

Re: Problem with cosine function

Post by Tuomas Miettinen » December 10th, 2014, 9:01 am

The only way that I know of how to use randomness is with sensitivity analysis experiments. We tried to implement a random variable as such a couple of years ago but didn't succeed too well. I think it was due to Modelica not supporting random numbers.

BR,
Tuomas
rosenm
Posts: 5
Joined: December 6th, 2014, 9:54 am

Re: Problem with cosine function

Post by rosenm » December 10th, 2014, 9:46 am

Thank you one more time!
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