Newspace parameters
comment: Compute space of new eigenforms
[N,k,chi] = [21,4,Mod(1,21)]
mf = mfinit([N,k,chi],0)
lf = mfeigenbasis(mf)
from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(21, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([0, 0]))
N = Newforms(chi, 4, names="a")
//Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("21.1");
S:= CuspForms(chi, 4);
N := Newforms(S);
| Level: | \( N \) | \(=\) | \( 21 = 3 \cdot 7 \) |
| Weight: | \( k \) | \(=\) | \( 4 \) |
| Character orbit: | \([\chi]\) | \(=\) | 21.a (trivial) |
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: | yes |
| Analytic conductor: | \(1.23904011012\) |
| Analytic rank: | \(0\) |
| Dimension: | \(1\) |
| Coefficient field: | \(\mathbb{Q}\) |
| Coefficient ring: | \(\mathbb{Z}\) |
| Coefficient ring index: | \( 1 \) |
| Twist minimal: | yes |
| Fricke sign: | \(+1\) |
| Sato-Tate group: | $\mathrm{SU}(2)$ |
$q$-expansion
comment: q-expansion
sage: f.q_expansion() # note that sage often uses an isomorphic number field
gp: mfcoefs(f, 20)
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 | \(\iota_m(\nu)\) | \( a_{2} \) | \( a_{3} \) | \( a_{4} \) | \( a_{5} \) | \( a_{6} \) | \( a_{7} \) | \( a_{8} \) | \( a_{9} \) | \( a_{10} \) | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1.1 |
|
4.00000 | −3.00000 | 8.00000 | −4.00000 | −12.0000 | −7.00000 | 0 | 9.00000 | −16.0000 | |||||||||||||||||||||
Atkin-Lehner signs
| \( p \) | Sign |
|---|---|
| \(3\) | \( +1 \) |
| \(7\) | \( +1 \) |
Inner twists
This newform does not admit any (nontrivial) inner twists.
Twists
| By twisting character orbit | |||||||
|---|---|---|---|---|---|---|---|
| Char | Parity | Ord | Mult | Type | Twist | Min | Dim |
| 1.a | even | 1 | 1 | trivial | 21.4.a.b | ✓ | 1 |
| 3.b | odd | 2 | 1 | 63.4.a.a | 1 | ||
| 4.b | odd | 2 | 1 | 336.4.a.h | 1 | ||
| 5.b | even | 2 | 1 | 525.4.a.b | 1 | ||
| 5.c | odd | 4 | 2 | 525.4.d.b | 2 | ||
| 7.b | odd | 2 | 1 | 147.4.a.g | 1 | ||
| 7.c | even | 3 | 2 | 147.4.e.c | 2 | ||
| 7.d | odd | 6 | 2 | 147.4.e.b | 2 | ||
| 8.b | even | 2 | 1 | 1344.4.a.w | 1 | ||
| 8.d | odd | 2 | 1 | 1344.4.a.i | 1 | ||
| 12.b | even | 2 | 1 | 1008.4.a.m | 1 | ||
| 15.d | odd | 2 | 1 | 1575.4.a.k | 1 | ||
| 21.c | even | 2 | 1 | 441.4.a.b | 1 | ||
| 21.g | even | 6 | 2 | 441.4.e.n | 2 | ||
| 21.h | odd | 6 | 2 | 441.4.e.m | 2 | ||
| 28.d | even | 2 | 1 | 2352.4.a.l | 1 | ||
| By twisted newform orbit | |||||||
|---|---|---|---|---|---|---|---|
| Twist | Min | Dim | Char | Parity | Ord | Mult | Type |
| 21.4.a.b | ✓ | 1 | 1.a | even | 1 | 1 | trivial |
| 63.4.a.a | 1 | 3.b | odd | 2 | 1 | ||
| 147.4.a.g | 1 | 7.b | odd | 2 | 1 | ||
| 147.4.e.b | 2 | 7.d | odd | 6 | 2 | ||
| 147.4.e.c | 2 | 7.c | even | 3 | 2 | ||
| 336.4.a.h | 1 | 4.b | odd | 2 | 1 | ||
| 441.4.a.b | 1 | 21.c | even | 2 | 1 | ||
| 441.4.e.m | 2 | 21.h | odd | 6 | 2 | ||
| 441.4.e.n | 2 | 21.g | even | 6 | 2 | ||
| 525.4.a.b | 1 | 5.b | even | 2 | 1 | ||
| 525.4.d.b | 2 | 5.c | odd | 4 | 2 | ||
| 1008.4.a.m | 1 | 12.b | even | 2 | 1 | ||
| 1344.4.a.i | 1 | 8.d | odd | 2 | 1 | ||
| 1344.4.a.w | 1 | 8.b | even | 2 | 1 | ||
| 1575.4.a.k | 1 | 15.d | odd | 2 | 1 | ||
| 2352.4.a.l | 1 | 28.d | even | 2 | 1 | ||
Hecke kernels
This newform subspace can be constructed as the kernel of the linear operator
\( T_{2} - 4 \)
acting on \(S_{4}^{\mathrm{new}}(\Gamma_0(21))\).
Hecke characteristic polynomials
| $p$ | $F_p(T)$ |
|---|---|
| $2$ |
\( T - 4 \)
|
| $3$ |
\( T + 3 \)
|
| $5$ |
\( T + 4 \)
|
| $7$ |
\( T + 7 \)
|
| $11$ |
\( T - 62 \)
|
| $13$ |
\( T + 62 \)
|
| $17$ |
\( T - 84 \)
|
| $19$ |
\( T - 100 \)
|
| $23$ |
\( T + 42 \)
|
| $29$ |
\( T + 10 \)
|
| $31$ |
\( T + 48 \)
|
| $37$ |
\( T + 246 \)
|
| $41$ |
\( T + 248 \)
|
| $43$ |
\( T - 68 \)
|
| $47$ |
\( T - 324 \)
|
| $53$ |
\( T - 258 \)
|
| $59$ |
\( T - 120 \)
|
| $61$ |
\( T - 622 \)
|
| $67$ |
\( T - 904 \)
|
| $71$ |
\( T + 678 \)
|
| $73$ |
\( T + 642 \)
|
| $79$ |
\( T - 740 \)
|
| $83$ |
\( T - 468 \)
|
| $89$ |
\( T - 200 \)
|
| $97$ |
\( T + 1266 \)
|
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