Convert LaTeX -> SymPy -> evaluate -> LaTeX in Python3 and GNU Emacs.

1. Install Python3 (tested using v3.11.2).
2. Install SymPy (tested using v1.11.1).
3. The Python3 package antlr4-python3-runtime. Please follow the installation instructions here. The version of antlr4-python3-runtime recommended on this webpage might differ from your requirement: for example, I needed version v4.10 for SymPy v1.11.1. Please run the following Python code before installing antlr4-python3-runtime to determine the desired version.

   >>> from sympy.parsing.latex import parse_latex
   >>> parse_latex("\int")

4. Optional: Install GNU Emacs.

1. Clone this repository.
2. Copy the file computex.py to some directory that is in the PATH environment variable of your Operating system.

Run computex.py -h to get help.

Create a file named matsq.tex with the following contents:

\begin{pmatrix}
a & b \\
c & d \\
\end{pmatrix}^2

and another one named matmult.tex with the following contents:

\begin{pmatrix}
a & b \\
c & d \\
\end{pmatrix}\begin{pmatrix}
e & f \\
g & h \\
\end{pmatrix}

Now, try the following commands in a UNIX shell:

$ cat matsq.tex | computex.py
$ cat matmult.tex | computex.py

Try these to print the output in equation form:

$ cat matsq.tex | computex.py -e
$ cat matmult.tex | computex.py -e

If you are using Windows and do not have cat, then try using the type command instead.

This step is optional.

1. If you wish the key bindings to be available in all buffers, then add the following to your emacs Initialization File:

   (setq computex-file "/path/to/computex.el")
   (if (file-exists-p computex-file)
       (progn (load computex-file)
              (global-set-key (kbd "C-`") sgang-computex-map)))

   If you are using emacs 29 or above, then consider using keymap-global-set instead of global-set-key.
2. If you wish the key bindings to be available only in latex-mode of AUCTeX, then add the following to your emacs Initialization File instead:

   (setq computex-file "/path/to/computex.el")
   (if (file-exists-p computex-file)
      (progn (load computex-file)
             (eval-after-load 'latex
               '(define-key LaTeX-mode-map (kbd "C-`") sgang-computex-map))))

3. Optional: Change the "C-`" above to any key you wish.

1. Select the LaTeX code to evaluate (excluding any $-sign or other math delimiters).
2. Call any of the functions sgang-tex-computex-* defined in computex.el. Assuming that C-` is bound to sgang-computex-map, type C-` followed by:
   • the key z for sgang-tex-computex corresponding to computex.py -e,
   • the key e for sgang-tex-computex-expand corresponding to computex.py -e -E,
   • the key f for sgang-tex-compute-factorize corresponding to computex.py -e -f,
   • the key s for sgang-tex-compute-simplify corresponding to computex.py -e -s.

This idea was borrowed from symtex.el authored by @ultronozm.