Newspace parameters
comment: Compute space of new eigenforms
[N,k,chi] = [841,2,Mod(840,841)]
mf = mfinit([N,k,chi],0)
lf = mfeigenbasis(mf)
from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(841, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([1]))
N = Newforms(chi, 2, names="a")
//Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("841.840");
S:= CuspForms(chi, 2);
N := Newforms(S);
| Level: | \( N \) | \(=\) | \( 841 = 29^{2} \) |
| Weight: | \( k \) | \(=\) | \( 2 \) |
| Character orbit: | \([\chi]\) | \(=\) | 841.b (of order \(2\), degree \(1\), not minimal) |
Newform invariants
comment: select newform
sage: f = N[0] # Warning: the index may be different
gp: f = lf[1] \\ Warning: the index may be different
| Self dual: | no |
| Analytic conductor: | \(6.71541880999\) |
| Analytic rank: | \(0\) |
| Dimension: | \(4\) |
| Coefficient field: | \(\Q(i, \sqrt{5})\) |
|
comment: defining polynomial
gp: f.mod \\ as an extension of the character field
|
|
| Defining polynomial: |
\( x^{4} + 3x^{2} + 1 \)
|
| Coefficient ring: | \(\Z[a_1, a_2]\) |
| Coefficient ring index: | \( 1 \) |
| Twist minimal: | yes |
| Sato-Tate group: | $\mathrm{SU}(2)[C_{2}]$ |
$q$-expansion
comment: q-expansion
sage: f.q_expansion() # note that sage often uses an isomorphic number field
gp: mfcoefs(f, 20)
Coefficients of the \(q\)-expansion are expressed in terms of a basis \(1,\beta_1,\beta_2,\beta_3\) for the coefficient ring described below. We also show the integral \(q\)-expansion of the trace form.
Basis of coefficient ring in terms of a root \(\nu\) of
\( x^{4} + 3x^{2} + 1 \)
:
| \(\beta_{1}\) | \(=\) |
\( \nu \)
|
| \(\beta_{2}\) | \(=\) |
\( \nu^{2} + 1 \)
|
| \(\beta_{3}\) | \(=\) |
\( \nu^{3} + 2\nu \)
|
| \(\nu\) | \(=\) |
\( \beta_1 \)
|
| \(\nu^{2}\) | \(=\) |
\( \beta_{2} - 1 \)
|
| \(\nu^{3}\) | \(=\) |
\( \beta_{3} - 2\beta_1 \)
|
Character values
We give the values of \(\chi\) on generators for \(\left(\mathbb{Z}/841\mathbb{Z}\right)^\times\).
| \(n\) | \(2\) |
| \(\chi(n)\) | \(-1\) |
Embeddings
For each embedding \(\iota_m\) of the coefficient field, the values \(\iota_m(a_n)\) are shown below.
For more information on an embedded modular form you can click on its label.
comment: embeddings in the coefficient field
gp: mfembed(f)
| Label | \(\iota_m(\nu)\) | \( a_{2} \) | \( a_{3} \) | \( a_{4} \) | \( a_{5} \) | \( a_{6} \) | \( a_{7} \) | \( a_{8} \) | \( a_{9} \) | \( a_{10} \) | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 840.1 |
|
− | 1.61803i | 1.61803i | −0.618034 | 2.85410 | 2.61803 | 2.23607 | − | 2.23607i | 0.381966 | − | 4.61803i | |||||||||||||||||||||||||||
| 840.2 | − | 0.618034i | 0.618034i | 1.61803 | −3.85410 | 0.381966 | −2.23607 | − | 2.23607i | 2.61803 | 2.38197i | |||||||||||||||||||||||||||||
| 840.3 | 0.618034i | − | 0.618034i | 1.61803 | −3.85410 | 0.381966 | −2.23607 | 2.23607i | 2.61803 | − | 2.38197i | |||||||||||||||||||||||||||||
| 840.4 | 1.61803i | − | 1.61803i | −0.618034 | 2.85410 | 2.61803 | 2.23607 | 2.23607i | 0.381966 | 4.61803i | ||||||||||||||||||||||||||||||
Inner twists
| Char | Parity | Ord | Mult | Type |
|---|---|---|---|---|
| 1.a | even | 1 | 1 | trivial |
| 29.b | even | 2 | 1 | inner |
Twists
| By twisting character orbit | |||||||
|---|---|---|---|---|---|---|---|
| Char | Parity | Ord | Mult | Type | Twist | Min | Dim |
| 1.a | even | 1 | 1 | trivial | 841.2.b.b | 4 | |
| 29.b | even | 2 | 1 | inner | 841.2.b.b | 4 | |
| 29.c | odd | 4 | 1 | 841.2.a.a | ✓ | 2 | |
| 29.c | odd | 4 | 1 | 841.2.a.c | yes | 2 | |
| 29.d | even | 7 | 6 | 841.2.e.j | 24 | ||
| 29.e | even | 14 | 6 | 841.2.e.j | 24 | ||
| 29.f | odd | 28 | 6 | 841.2.d.g | 12 | ||
| 29.f | odd | 28 | 6 | 841.2.d.i | 12 | ||
| 87.f | even | 4 | 1 | 7569.2.a.d | 2 | ||
| 87.f | even | 4 | 1 | 7569.2.a.l | 2 | ||
| By twisted newform orbit | |||||||
|---|---|---|---|---|---|---|---|
| Twist | Min | Dim | Char | Parity | Ord | Mult | Type |
| 841.2.a.a | ✓ | 2 | 29.c | odd | 4 | 1 | |
| 841.2.a.c | yes | 2 | 29.c | odd | 4 | 1 | |
| 841.2.b.b | 4 | 1.a | even | 1 | 1 | trivial | |
| 841.2.b.b | 4 | 29.b | even | 2 | 1 | inner | |
| 841.2.d.g | 12 | 29.f | odd | 28 | 6 | ||
| 841.2.d.i | 12 | 29.f | odd | 28 | 6 | ||
| 841.2.e.j | 24 | 29.d | even | 7 | 6 | ||
| 841.2.e.j | 24 | 29.e | even | 14 | 6 | ||
| 7569.2.a.d | 2 | 87.f | even | 4 | 1 | ||
| 7569.2.a.l | 2 | 87.f | even | 4 | 1 | ||
Hecke kernels
This newform subspace can be constructed as the kernel of the linear operator
\( T_{2}^{4} + 3T_{2}^{2} + 1 \)
acting on \(S_{2}^{\mathrm{new}}(841, [\chi])\).
Hecke characteristic polynomials
| $p$ | $F_p(T)$ |
|---|---|
| $2$ |
\( T^{4} + 3T^{2} + 1 \)
|
| $3$ |
\( T^{4} + 3T^{2} + 1 \)
|
| $5$ |
\( (T^{2} + T - 11)^{2} \)
|
| $7$ |
\( (T^{2} - 5)^{2} \)
|
| $11$ |
\( T^{4} + 15T^{2} + 25 \)
|
| $13$ |
\( (T^{2} + 4 T - 1)^{2} \)
|
| $17$ |
\( T^{4} + 63T^{2} + 841 \)
|
| $19$ |
\( T^{4} + 27T^{2} + 81 \)
|
| $23$ |
\( (T^{2} - 2 T - 4)^{2} \)
|
| $29$ |
\( T^{4} \)
|
| $31$ |
\( T^{4} + 103T^{2} + 121 \)
|
| $37$ |
\( T^{4} + 98T^{2} + 1681 \)
|
| $41$ |
\( T^{4} + 23T^{2} + 121 \)
|
| $43$ |
\( T^{4} + 60T^{2} + 400 \)
|
| $47$ |
\( (T^{2} + 49)^{2} \)
|
| $53$ |
\( (T + 2)^{4} \)
|
| $59$ |
\( (T^{2} - T - 31)^{2} \)
|
| $61$ |
\( T^{4} + 3T^{2} + 1 \)
|
| $67$ |
\( (T^{2} - 12 T + 16)^{2} \)
|
| $71$ |
\( (T^{2} + 12 T + 16)^{2} \)
|
| $73$ |
\( T^{4} + 188T^{2} + 16 \)
|
| $79$ |
\( T^{4} + 63T^{2} + 961 \)
|
| $83$ |
\( (T^{2} + 2 T - 79)^{2} \)
|
| $89$ |
\( T^{4} + 98T^{2} + 1681 \)
|
| $97$ |
\( T^{4} + 287T^{2} + 3481 \)
|
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