On 10/31/07, Paul Zimmermann <[EMAIL PROTECTED]> wrote:
> I am trying to switch to Sage for my usual computations (this will help me
> to better know the system for the Sage days 6). In particular I did not find
> how to automatically load the following Sage function I've written (my first
> one) [it does compute the factored group order of a lucky elliptic curve which

You should put the function in a file, anywhere on your system, called
e.g.,
   myfile.sage

then from sage type

   load "myfile.sage"


> found the factor p; s is the "sigma" parameter used by most ECM software]:

By the way, GMP-ECM is part of Sage.

  sage: ecm?
  sage: ecm.[tab key]
  sage: sage: ecm.factor(next_prime(10^15)*next_prime(10^40))
  [1000000000000037, 10000000000000000000000000000000000000121]

There is also a function DistributedFactor that uses GMP-ECM
and Bill Hart's quadratic sieve to factor integers using Sage's
distributed job server:
  sage: help(DistributedFactor)

Unfortunately, the documentation for DistributedFactor doesn't
make it at all trivial to use yet, so you might not want to try it.


>
>    def FindGroupOrder(p,s):
>       K = GF(p)
>       v = K(4*s)
>       u = K(s^2-5)
>       x = u^3
>       b = 4*x*v
>       a = (v-u)^3*(3*u+v)
>       A = a/b-2
>       x = x/v^3
>       b = x^3 + A*x^2 + x
>       E = EllipticCurve(K,[0,b*A,0,b^2,0])
>       return factor(E.cardinality())
>
> I tried to put it in $HOME/.sagerc but it did not work.

There is no .sagerc recoginized by sage.  There is a file

  $HOME/.sage/init.sage

that if it exists will be autoloaded by Sage on startup.

>  I noticed there is
> a $HOME/.sage directory. I tried to put it in $HOME/.sage/ipy_user_conf.py,
> but it did not work either.

That's for ipython, which is the command-line front end
used by Sage.

> [Feel free to tell me if I abuse by asking you such questions. I tried to
> subscribe to the sage google group, but it seems you have first to create a
> google account, and I'm reluctant to do this.]

You can subscribe to that list without creating a google account
if somebody invites you.  I'll invite you.

 -- William

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