> E = EllipticCurve([0,-39409298,0,5554231502,0])
> E.analytic_rank()

> (which, to be honest, I don't expect to terminate) then I get a RuntimeError.
> I thought that the yoga was "just read the last line if you're not an expert".
> The last line says

> RuntimeError: error '  ***   error opening input file: /home/buzzard/.sage/
>                                   ^--------------------' running 'ellanalyticrank(ellinit([0, 1, 0, -517692035386099,
> -4533726894914038913619]),0)'

> ??

> Kevin Buzzard just told me about this rather weird error he'd got:

>> If I fire up sage (version 4.0.1) and then type

>> E = EllipticCurve([0,-39409298,0,5554231502,0])
>> E.analytic_rank()

>> (which, to be honest, I don't expect to terminate) then I get a RuntimeError.
>> I thought that the yoga was "just read the last line if you're not an expert".
>> The last line says

>> RuntimeError: error '  ***   error opening input file: /home/buzzard/.sage/
>>                                   ^--------------------' running 'ellanalyticrank(ellinit([0, 1, 0, -517692035386099,
>> -4533726894914038913619]),0)'

>> ??

> I got the same error in 4.1.2.alpha4. The full traceback (below)
> suggests that this has something to with the code in extcode/pari/
> cremona; but it would be nice if it could fail a bit more gracefully!

> sage: E = EllipticCurve([0,-39409298,0,5554231502,0])
> sage: E.analytic_rank()
> ---------------------------------------------------------------------------
> RuntimeError                              Traceback (most recent call
> last)

> /home/david/.sage/temp/rockhopper/5225/
> _home_david__sage_init_sage_0.py in <module>()

> /home/david/sage-4.1.2.alpha4/local/lib/python2.6/site-packages/sage/
> schemes/elliptic_curves/ell_rational_field.pyc in analytic_rank(self,
> algorithm)
>   1354
> """
>   1355         if algorithm ==
> 'cremona':
> -> 1356             return rings.Integer(gp_cremona.ellanalyticrank
> (self.minimal_model().a_invariants()))
>   1357         elif algorithm ==
> 'rubinstein':
>   1358
> try:

> /home/david/sage-4.1.2.alpha4/local/lib/python2.6/site-packages/sage/
> schemes/elliptic_curves/gp_cremona.pyc in ellanalyticrank
> (e)
>    100     while
> True:
>    101
> try:
> --> 102             return ellanalyticrank_prec(e,
> prec)
>    103         except
> RuntimeError,msg:
>    104             if 'precision too low' in str
> (msg):

> /home/david/sage-4.1.2.alpha4/local/lib/python2.6/site-packages/sage/
> schemes/elliptic_curves/gp_cremona.pyc in ellanalyticrank_prec(e,
> prec)
>     74     if prec: gp.set_real_precision
> (old_prec)
>     75     if x.find("***") !=
> -1:
> ---> 76         raise RuntimeError, "error '%s' running '%s'"%
> (x,cmd)
>     77     return Integer
> (x)

> 78

> RuntimeError: error '  ***   error opening input file: /home/
> david/.sage//t
>                                  ^--------------------' running
> 'ellanalyticrank(ellinit([0, 1, 0, -517692035386099,
> -4533726894914038913619]),0)'