Problem with SympyBridge

Question

I am attempting to use SympyBridge to simplify a somewhat involved algebraic expression and it appears to be throwing a python error. Here is the notebook

https://drive.google.com/file/d/16jcPyMk7OkSsiShWLiYIw_7ng7-MUdFG/view?usp=sharing

The error message  after the call to SympyBridge is

\begin{verbatim}TokenError: ('unexpected character after line continuation character', (1, 82))

At:   /usr/lib/python3.12/tokenize.py(582): _generate_tokens_from_c_tokenizer   /usr/lib/python3/dist-packages/sympy/parsing/sympy_parser.py(891): stringify_expr   /usr/lib/python3/dist-packages/sympy/parsing/sympy_parser.py(1072): parse_expr   Notebook Cell (Line 1): ex_sympy = sbb.to_sympy() \end{verbatim}

I have used SympyBridge on simpler expressions like those in the Cadabra Book and it works fine....

Answer 1

It chokes on the backslash in the \Dg, because Python does not like backslashes in variable names. All "normal" LaTeX symbols get (e.g. \alpha) get their backslash stripped and then re-instated afterwards, but if you use custom symbols that will not work.

Since you are already using a LaTeXForm to make the output look nice, I would just use Dg instead of \Dg everywhere. That will work.

Comments

Thanks Kasper that works