# $$L$$-series of modular abelian varieties¶

AUTHOR:

• William Stein (2007-03)

class sage.modular.abvar.lseries.Lseries(abvar)

Base class for $$L$$-series attached to modular abelian varieties.

This is a common base class for complex and $$p$$-adic $$L$$-series of modular abelian varieties.

abelian_variety()

Return the abelian variety that this $$L$$-series is attached to.

OUTPUT:

a modular abelian variety

EXAMPLES:

sage: J0(11).padic_lseries(7).abelian_variety()
Abelian variety J0(11) of dimension 1

class sage.modular.abvar.lseries.Lseries_complex(abvar)

A complex $$L$$-series attached to a modular abelian variety.

EXAMPLES:

sage: A = J0(37)
sage: A.lseries()
Complex L-series attached to Abelian variety J0(37) of dimension 2

lratio()

Return the rational part of this $$L$$-function at the central critical value 1.

OUTPUT:

a rational number

EXAMPLES:

sage: A, B = J0(43).decomposition()
sage: A.lseries().rational_part()
0
sage: B.lseries().rational_part()
2/7

rational_part()

Return the rational part of this $$L$$-function at the central critical value 1.

OUTPUT:

a rational number

EXAMPLES:

sage: A, B = J0(43).decomposition()
sage: A.lseries().rational_part()
0
sage: B.lseries().rational_part()
2/7

vanishes_at_1()

Return True if $$L(1)=0$$ and return False otherwise.

OUTPUT:

a boolean

EXAMPLES:

Numerically, the $$L$$-series for $$J_0(389)$$ appears to vanish at 1. This is confirmed by this algebraic computation:

sage: L = J0(389).lseries(); L
Complex L-series attached to Simple abelian subvariety 389a(1,389) of dimension 1 of J0(389)
sage: L(1) # long time (2s) abstol 1e-10
-1.33139759782370e-19
sage: L.vanishes_at_1()
True


Numerically, one might guess that the $$L$$-series for $$J_1(23)$$ and $$J_1(31)$$ vanish at 1. This algebraic computation shows otherwise:

sage: L = J1(23).lseries(); L
Complex L-series attached to Abelian variety J1(23) of dimension 12
sage: L(1)  # long time (about 3 s)
0.0001295198...
sage: L.vanishes_at_1()
False
sage: abs(L(1, prec=100)- 0.00012951986142702571478817757148) < 1e-32  # long time (about 3 s)
True

sage: L = J1(31).lseries(); L
Complex L-series attached to Abelian variety J1(31) of dimension 26
sage: abs(L(1) - 3.45014267547611e-7) < 1e-15  # long time (about 8 s)
True
sage: L.vanishes_at_1()  # long time (about 6 s)
False


A $$p$$-adic $$L$$-series attached to a modular abelian variety.

power_series(n=2, prec=5)

Return the $$n$$-th approximation to this $$p$$-adic $$L$$-series as a power series in $$T$$.

Each coefficient is a $$p$$-adic number whose precision is provably correct.

NOTE: This is not yet implemented.

EXAMPLES:

sage: L = J0(37).padic_lseries(5)
sage: L.power_series()
Traceback (most recent call last):
...
NotImplementedError
sage: L.power_series(3,7)
Traceback (most recent call last):
...
NotImplementedError

prime()

Return the prime $$p$$ of this $$p$$-adic $$L$$-series.

EXAMPLES:

sage: J0(11).padic_lseries(7).prime()
7