gp-inline tests in a document

[Kevin Ryde <user42_kevin@yahoo.com.au>]

In the unending battle against errors, I've been using gp to check
formulas and sample values in TeX and elsewhere by writing test
expressions as comments like "% GP-Test 2+2==4".  A gp-inline script
(Perl) extracts and executes.

    http://user42.tuxfamily.org/pari-gp-inline/index.html

Tests in with the text help give some confidence to a claimed formula
etc, especially if returning to the text later and being tempted to
rearrange :-).

There's a couple of lines of elisp for passing the expressions to
pariemacs gp subprocess.  That can be any comment too so handy for gp
one-liners as experiments etc elsewhere, eg. in program code.