Kannappan Sampath on Wed, 03 Feb 2021 23:20:00 +0100


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Re: parsing pari output for mfgaloistype in weight 1

Please ignore my earlier message; since updating my Fedora, I see that my Pari has also updated.

                                       Best, 
                                       Kannappan 


---------
Kannappan Sampath
Graduate Student

Department of Mathematics | University of Michigan


On Wed, Feb 3, 2021 at 4:53 PM Kannappan Sampath <knsam@umich.edu> wrote:
Dear Prof. Allombert:

Thank you so much for your help! That's a relief!
I am on a Fedora machine and the usual package manager only seems to carry 2.11.
Do you know if there is a quick way for me to update? 

Thank you in advance for your help!


                                       Best, 
                                       Kannappan 


---------
Kannappan Sampath
Graduate Student

Department of Mathematics | University of Michigan


On Wed, Feb 3, 2021 at 4:09 AM Bill Allombert <Bill.Allombert@math.u-bordeaux.fr> wrote:
On Tue, Feb 02, 2021 at 07:24:03PM -0500, Kannappan Sampath wrote:
> Hello everyone:
>
> I wanted to search for weight 1 forms with a list of properties related to
> its level and conductor of its nebentypus. I have a question I'd like some
> help on. Thank you in advance for your help.
>
> Let's set
>
> mfall = mfinit([N, 1, 0], 0);
>
> Occasionally, the mfgaloistype(mfall[jj]) returns a list of length more
> than 1. I understood this to mean that forms with the given nebentypus have
> projective images as indicated by this list...  but that seems not to match
> with other databases containing similar data (most notably, lmfdb).
>
> Let me illustrate all this in a particular example I am looking at.
>
> ? default(parisize, 100000000);
>   ***   Warning: new stack size = 100000000 (95.367 Mbytes).
> ? mfall = mfinit([756, 1, 0], 0);
> ? mfgaloistype(mfall[1])
> % [6, 12]

Dear Kannappan,
This seems like a bug in PARI 2.11, please upgrade to PARI 2.13.1.

On my computer:
? mfall = mfinit([756, 1, 0], 0);
? mfgaloistype(mfall[1])
%2 = [12,12]

If you want to match it with the lmfdb, you should use
mfparams(mfall[1])
to find the corresponding character.

Cheers,
Bill