import cdb.sympy.solvers hangs the kernel

Question

Hi!

I just updated to the latest version (2.2.7, the git-master branch) and cannot use cdb.sympy.solvers anymore. On the version before, it was working just fine.

I also looked into the solvers.cnb notebook. While dsolve still does it's job, using linsolve causes the kernel to just load endlessly and I have to restart it.

I hope it is not just a problem with my python version, but i get this on two different pcs running on the latest Fedora with Python 3.7.3.

Best Regards, Karim

Comments

This looks like the parser hanging somewhere, probably related to the UTF8 changes that went into 2.2.7. Will have a look.

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Hello @kasper and @Karim. I've found a (perhaps) related bug. I was checking the example cadabra2/examples/sympy_examples.cnb, after a few evaluations, the prompt started to jump back to previous lines

Cadabra notebook shot

Notice that I evaluated expr.args; and the result was returned three cells before (when I assigned ex)

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That doesn't look related. @doxdrum, can you reproduce this? If not, do you remember whether you did anything else except evaluating cells?

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@kasper: I mention it could be related because the strange behaviour started after calling SymPy. I just opened the notebook provided on the git repository, and run it! without changing a single line.

I can assure that my system has a working SymPy instalation, it does work (for example) through map_sympy.

Answer 1

The new UTF8 parser barfed on a double backslash. Still not quite sure why, but I have corrected that in the core/packages/cdb/sympy/solvers.cnb file and this package should work now again. Update on github master.

Comments

Thanks for the fix! Quick as always :)