Broken typeset in pdf export of Jupyter notebook

[egourgoulhon]

In the Jupyter notebook, typeset outputs, either obtained by show or by %display latex, are no longer typeset in the pdf file generated by File->Download as->PDF via LaTeX (.pdf).

See ​https://groups.google.com/d/msg/sage-devel/LC_4PSjyx2M/I9ip8c0bCAAJ for more details, and in particular ​https://groups.google.com/d/msg/sage-devel/LC_4PSjyx2M/coAzvbo1CAAJ

[was]

See also: ​https://github.com/sagemathinc/cocalc/issues/2030

[embray]

As discussed on sage-devel, we need to make the Sage kernel be more explicit about when the output's mimetype is text/latex (instead of using text/html, which is generally unnecessary--I don't think we need to wrap the output in an HTML fragment or <script type="text/math">. I could be wrong, but I think that might be a vestige from older versions of IPython notebook...

[egourgoulhon]

A solution could be to use Jupyter's native rich output for LaTeX, not the Sage's mechanism through the IPython extension %display. For this, it suffices to implement the method _repr_latex_ to all Sage objects, i.e. add the following to SageObject:

    def _repr_latex_(self):
        from sage.misc.latex import latex
        return '$' + str(latex(self)) + '$'

See e.g. ​this presentation of Jupyter display logic. This solves the pdf issue reported here.

[egourgoulhon]

See ​https://groups.google.com/d/msg/sage-devel/nP7PKQyqxKw/IAWZb9nlAAAJ for a related sage-devel discussion.