Re: Question about mfpetersson

[Aurel Page <aurel.page@normalesup.org>]

    Dear Ahmad,
    
    It looks like a bug to me, but I will check with Karim and Henri who
    wrote this package.
    
    One line looks suspicious to me:
    
      if (!gequal0(gel(ESF,1)) && !gequal0(gel(ESG,1)))
        return mfpeterssonnoncusp(FS, GS);
    
    When changing && to ||, we obtain:
    
    ? mfpetersson(mfsymbol(mfDelta),
    mfsymbol(mflinear([mfDelta,mfEk(12)],[1,2])))
    %1 = 1.0353620568043209223478168122251645992 E-6 -
    1.4909815660416053635 E-42*I
    ? mfpetersson(mfsymbol(mfDelta),
    mfsymbol(mflinear([mfDelta,mfEk(12)],[1,0])))
    %2 = 1.0353620568043209223478168122251645932 E-6 + 0.E-44*I
    ? mfpetersson(mfsymbol(mfDelta),
    mfsymbol(mflinear([mfDelta,mfEk(12)],[0,1])))
    %3 = 1.1364530545674266445 E-42 - 5.829401611591239015 E-43*I
    
    But I may be misunderstanding what the code is supposed to do.
    
    Best,
    Aurel

On 17/03/2025 12:38, Ahmad Mostafa Ismail El-Guindy wrote:

Hello,

I am not sure what exactly am I doing wrong, but I am getting unexpected behavior from mfpetersson which seems to violate linearity. Since <Delta, E_{12}>=0 shouldn't the first line below give <Delta, Delta>? Why is it returning 0 instead?

(12:22) gp > mfpetersson(mfsymbol(mfDelta), mfsymbol(mflinear([mfDelta,mfEk(12)],[1,2])))

%43 = 0

(12:25) gp > mfpetersson(mfsymbol(mfDelta), mfsymbol(mflinear([mfDelta,mfEk(12)],[1,0])))

%44 = 1.0353620568043209223478168122251645932 E-6 + 0.E-44*I

(12:25) gp > mfpetersson(mfsymbol(mfDelta), mfsymbol(mflinear([mfDelta,mfEk(12)],[0,1])))

%45 = 0

Thanks,

Ahmad