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Properties

Label 16.0.28179280429...0000.4
Degree $16$
Signature $[0, 8]$
Discriminant $2^{40}\cdot 3^{8}\cdot 5^{8}$
Root discriminant $21.91$
Ramified primes $2, 3, 5$
Class number $4$
Class group $[4]$
Galois group $Q_8 : C_2^2$ (as 16T23)

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Show commands for: Magma / SageMath / Pari/GP

magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![1, 0, 44, 0, 968, 0, -876, 0, 398, 0, 36, 0, 8, 0, -4, 0, 1]);
 
sage: x = polygen(QQ); K.<a> = NumberField(x^16 - 4*x^14 + 8*x^12 + 36*x^10 + 398*x^8 - 876*x^6 + 968*x^4 + 44*x^2 + 1)
 
gp: K = bnfinit(x^16 - 4*x^14 + 8*x^12 + 36*x^10 + 398*x^8 - 876*x^6 + 968*x^4 + 44*x^2 + 1, 1)
 

Normalized defining polynomial

\( x^{16} - 4 x^{14} + 8 x^{12} + 36 x^{10} + 398 x^{8} - 876 x^{6} + 968 x^{4} + 44 x^{2} + 1 \)

magma: DefiningPolynomial(K);
 
sage: K.defining_polynomial()
 
gp: K.pol
 

Invariants

Degree:  $16$
magma: Degree(K);
 
sage: K.degree()
 
gp: poldegree(K.pol)
 
Signature:  $[0, 8]$
magma: Signature(K);
 
sage: K.signature()
 
gp: K.sign
 
Discriminant:  \(2817928042905600000000=2^{40}\cdot 3^{8}\cdot 5^{8}\)
magma: Discriminant(Integers(K));
 
sage: K.disc()
 
gp: K.disc
 
Root discriminant:  $21.91$
magma: Abs(Discriminant(Integers(K)))^(1/Degree(K));
 
sage: (K.disc().abs())^(1./K.degree())
 
gp: abs(K.disc)^(1/poldegree(K.pol))
 
Ramified primes:  $2, 3, 5$
magma: PrimeDivisors(Discriminant(Integers(K)));
 
sage: K.disc().support()
 
gp: factor(abs(K.disc))[,1]~
 
This field is not Galois over $\Q$.
This is not a CM field.

Integral basis (with respect to field generator \(a\))

$1$, $a$, $a^{2}$, $a^{3}$, $\frac{1}{2} a^{4} - \frac{1}{2}$, $\frac{1}{2} a^{5} - \frac{1}{2} a$, $\frac{1}{4} a^{6} - \frac{1}{4} a^{4} + \frac{1}{4} a^{2} - \frac{1}{4}$, $\frac{1}{4} a^{7} - \frac{1}{4} a^{5} + \frac{1}{4} a^{3} - \frac{1}{4} a$, $\frac{1}{8} a^{8} - \frac{1}{8}$, $\frac{1}{8} a^{9} - \frac{1}{8} a$, $\frac{1}{16} a^{10} - \frac{1}{16} a^{8} - \frac{1}{2} a^{3} + \frac{7}{16} a^{2} - \frac{1}{2} a - \frac{7}{16}$, $\frac{1}{16} a^{11} - \frac{1}{16} a^{9} + \frac{7}{16} a^{3} - \frac{1}{2} a^{2} - \frac{7}{16} a - \frac{1}{2}$, $\frac{1}{336} a^{12} + \frac{1}{84} a^{10} + \frac{5}{112} a^{8} - \frac{1}{12} a^{6} + \frac{17}{112} a^{4} + \frac{4}{21} a^{2} + \frac{37}{336}$, $\frac{1}{672} a^{13} - \frac{1}{672} a^{12} + \frac{1}{168} a^{11} - \frac{1}{168} a^{10} - \frac{9}{224} a^{9} + \frac{9}{224} a^{8} - \frac{1}{24} a^{7} + \frac{1}{24} a^{6} + \frac{17}{224} a^{5} - \frac{17}{224} a^{4} + \frac{2}{21} a^{3} - \frac{2}{21} a^{2} + \frac{79}{672} a - \frac{79}{672}$, $\frac{1}{491232} a^{14} - \frac{5}{163744} a^{12} + \frac{4559}{491232} a^{10} + \frac{28835}{491232} a^{8} + \frac{56023}{491232} a^{6} + \frac{119719}{491232} a^{4} - \frac{1}{2} a^{3} + \frac{4339}{163744} a^{2} - \frac{1}{2} a - \frac{46651}{491232}$, $\frac{1}{982464} a^{15} - \frac{1}{982464} a^{14} - \frac{5}{327488} a^{13} + \frac{5}{327488} a^{12} - \frac{26143}{982464} a^{11} + \frac{26143}{982464} a^{10} + \frac{59537}{982464} a^{9} - \frac{59537}{982464} a^{8} - \frac{66785}{982464} a^{7} + \frac{66785}{982464} a^{6} - \frac{3089}{982464} a^{5} + \frac{3089}{982464} a^{4} + \frac{55509}{327488} a^{3} - \frac{55509}{327488} a^{2} + \frac{45455}{982464} a - \frac{45455}{982464}$

magma: IntegralBasis(K);
 
sage: K.integral_basis()
 
gp: K.zk
 

Class group and class number

$C_{4}$, which has order $4$

magma: ClassGroup(K);
 
sage: K.class_group().invariants()
 
gp: K.clgp
 

Unit group

magma: UK, f := UnitGroup(K);
 
sage: UK = K.unit_group()
 
Rank:  $7$
magma: UnitRank(K);
 
sage: UK.rank()
 
gp: K.fu
 
Torsion generator:  \( \frac{15761}{491232} a^{14} - \frac{62437}{491232} a^{12} + \frac{41431}{163744} a^{10} + \frac{570067}{491232} a^{8} + \frac{2097709}{163744} a^{6} - \frac{13531939}{491232} a^{4} + \frac{14982515}{491232} a^{2} + \frac{226999}{163744} \) (order $8$)
magma: K!f(TU.1) where TU,f is TorsionUnitGroup(K);
 
sage: UK.torsion_generator()
 
gp: K.tu[2]
 
Fundamental units:  Units are too long to display, but can be downloaded with other data for this field from 'Stored data to gp' link to the right
magma: [K!f(g): g in Generators(UK)];
 
sage: UK.fundamental_units()
 
gp: K.fu
 
Regulator:  \( 62960.4974605 \)
magma: Regulator(K);
 
sage: K.regulator()
 
gp: K.reg
 

Galois group

$Q_8:C_2^2$ (as 16T23):

magma: GaloisGroup(K);
 
sage: K.galois_group(type='pari')
 
gp: polgalois(K.pol)
 
A solvable group of order 32
The 17 conjugacy class representatives for $Q_8 : C_2^2$
Character table for $Q_8 : C_2^2$

Intermediate fields

\(\Q(\sqrt{-1}) \), \(\Q(\sqrt{-2}) \), \(\Q(\sqrt{15}) \), \(\Q(\sqrt{30}) \), \(\Q(\sqrt{2}) \), \(\Q(\sqrt{-15}) \), \(\Q(\sqrt{-30}) \), \(\Q(\sqrt{2}, \sqrt{-15})\), \(\Q(\zeta_{8})\), \(\Q(\sqrt{2}, \sqrt{15})\), \(\Q(i, \sqrt{15})\), \(\Q(\sqrt{-2}, \sqrt{-15})\), \(\Q(\sqrt{-2}, \sqrt{15})\), \(\Q(i, \sqrt{30})\), 8.0.3317760000.4, 8.0.235929600.1 x2, 8.4.53084160000.3 x2

Fields in the database are given up to isomorphism. Isomorphic intermediate fields are shown with their multiplicities.

Sibling fields

Galois closure: data not computed
Degree 8 siblings: data not computed
Degree 16 siblings: data not computed

Frobenius cycle types

$p$ 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59
Cycle type R R R ${\href{/LocalNumberField/7.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/11.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/13.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/17.2.0.1}{2} }^{4}{,}\,{\href{/LocalNumberField/17.1.0.1}{1} }^{8}$ ${\href{/LocalNumberField/19.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/23.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/29.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/31.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/37.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/41.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/43.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/47.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/53.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/59.4.0.1}{4} }^{4}$

In the table, R denotes a ramified prime. Cycle lengths which are repeated in a cycle type are indicated by exponents.

magma: p := 7; // to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$:
 
magma: idealfactors := Factorization(p*Integers(K)); // get the data
 
magma: [<primefactor[2], Valuation(Norm(primefactor[1]), p)> : primefactor in idealfactors];
 
sage: p = 7; # to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$:
 
sage: [(e, pr.norm().valuation(p)) for pr,e in K.factor(p)]
 
gp: p = 7; \\ to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$:
 
gp: idealfactors = idealprimedec(K, p); \\ get the data
 
gp: vector(length(idealfactors), j, [idealfactors[j][3], idealfactors[j][4]])
 

Local algebras for ramified primes

$p$LabelPolynomial $e$ $f$ $c$ Galois group Slope content
$2$2.8.20.53$x^{8} + 4 x^{5} + 2 x^{4} + 2$$8$$1$$20$$Q_8:C_2$$[2, 3, 3]^{2}$
2.8.20.53$x^{8} + 4 x^{5} + 2 x^{4} + 2$$8$$1$$20$$Q_8:C_2$$[2, 3, 3]^{2}$
$3$3.4.2.1$x^{4} + 9 x^{2} + 36$$2$$2$$2$$C_2^2$$[\ ]_{2}^{2}$
3.4.2.1$x^{4} + 9 x^{2} + 36$$2$$2$$2$$C_2^2$$[\ ]_{2}^{2}$
3.4.2.1$x^{4} + 9 x^{2} + 36$$2$$2$$2$$C_2^2$$[\ ]_{2}^{2}$
3.4.2.1$x^{4} + 9 x^{2} + 36$$2$$2$$2$$C_2^2$$[\ ]_{2}^{2}$
$5$5.8.4.1$x^{8} + 10 x^{6} + 125 x^{4} + 2500$$2$$4$$4$$C_4\times C_2$$[\ ]_{2}^{4}$
5.8.4.1$x^{8} + 10 x^{6} + 125 x^{4} + 2500$$2$$4$$4$$C_4\times C_2$$[\ ]_{2}^{4}$