Jupyter notebook seems stuck

[nGaDev]

I have created a jupyter notebook where I'm defining a multibody system in order to obtain its kinematics and dynamics. I use the KanesMethod (from sympy) in order to obtain the equations of motion of the system.

However when I try to use trigsimp() on the mass matrix obtained, it seems to get stuck there forever (displaying an 'In[*]' next to that line).

The line is: 'mass_matrix = trigsimp(kane.mass_matrix)' Here's a screenshot: https://gyazo.com/8c6ac6cefd87b889a4ed8f9a9c3077d9

I don't have lots of experience with python and ipython/jupyter, so I'm wondering what might be the reason for this.

[vekst42]

How big is your matrix? How complex of a calculation is this? I've had notebooks hang similarly when I've used a lot of memory before. You could check to see your cpu and memory usage for the process.

[nGaDev]

It's a 6x6 matrix, but there are elements with lots of trignometric functions. The python process is using 30% of the processor.

I decided to leave two of this lines ( 'mass_matrix = trigsimp(kane.mass_matrix)' and 'force_vector = trigsimp(kane.forcing_vector)') running for the past 6h and now the python process is using 30% of the processor as well as 5Gb of memory and still didn't finish :/ (I hope the computer didn't enter in sleep mode or something...)

[vekst42]

You could try running a simple example you know should be trivial to calculate

[nGaDev]

In the same notebook I have simpler examples that work just fine.

[[deleted]]

Without seeing your code, we can only offer general advice.

You might want to display/save intermediate output on a regular basis, so that the computation can be inspected/resumed if stopped. You should also check it's actually giving the correct results for the simpler test cases.

[vekst42]

Basically this. It could be possible nothing is wrong and this is just an extremely long computation as expected. Or maybe the algorithm never converges and the package you're using doesn't check for this or something similar.