Comment (by Roland Haas):

It's in the Cactus flesh repo, repos/flesh/doc/latex/cactus.sty . However, when writing Cactus documentation in the doc directory of a thorn, usually you can put in (well you should not have to put in anything assuming you start from either the template generated by make newthorn or copy and pasted an existing documentation.tex file [and you are doing that aren’t you?]):

\usepackage{../../../../doc/latex/cactus}

The unusual case where this fails if when the directory structure does not match the expected one, usually b/c your repository structure is not REPO_ROOT/Thorn/doc/documentation.tex but eg instead REPO_ROOT/CactusCode/Thorn/doc/documentation.tex (eg done by RePrimAnd). Even in that case you should still put in the path shown above, even if this makes running:

cd repos/foo/docs
pdflatex documentation.tex

fail. Reason being that in fact you are not expected to run pdflatex yourself, but instead run make FOO-ThornDoc which will need that path (and will fail otherwise and thus the web-documtentaion will fail and your thorn won’t be seen be anyone).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2747/inclusion-of-sgrid-importer-in-einstein