Bill Allombert on Thu, 18 Feb 2016 08:10:31 +0100

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Re: Query from a gp newbie

On Thu, Feb 18, 2016 at 01:45:08AM +0000, Timothy Murphy wrote:
> What exactly is the relation between elldata and Cremona's tables?

elldata contains all curves in Cremona's tables, but not all fields
that are present in Cremona's tables.

> If elldata does not contain all Cremona's tables,
> what is the simplest way to access Cremona's data
> given the name of a curve, eg "880a1", returned by ellidentify?

Probably the simplest way is:

You can also do
? ellsearch("880a1")
%29 = ["880a1",[0,0,0,2,3],[[3,6]]]

> I am running gp on a Fedora-23 laptop, having installed it
> from Fedora's pari-* packages.
> I see that elldata was installed in /usr/share/pari/,
> while you recommend placing your recent elldata
> in /usr/local/share/pari.

Linux distributions put files and binaries in the /usr/share and
/usr/bin directory, while locally installed software are normally
placed in /usr/local/share and /usr/local/bin

Inside GP you can do
? default(datadir)
%1 = "/usr/share/pari"

to know where PARI is looking for extra data files.