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Properties

Label 16.0.26843545600...0000.4
Degree $16$
Signature $[0, 8]$
Discriminant $2^{40}\cdot 5^{12}$
Root discriminant $18.91$
Ramified primes $2, 5$
Class number $2$
Class group $[2]$
Galois group $C_2^2.D_4$ (as 16T33)

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Show commands for: Magma / SageMath / Pari/GP

magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![5, -40, 180, -540, 1196, -2052, 2820, -3180, 3001, -2380, 1576, -860, 386, -140, 40, -8, 1]);
 
sage: x = polygen(QQ); K.<a> = NumberField(x^16 - 8*x^15 + 40*x^14 - 140*x^13 + 386*x^12 - 860*x^11 + 1576*x^10 - 2380*x^9 + 3001*x^8 - 3180*x^7 + 2820*x^6 - 2052*x^5 + 1196*x^4 - 540*x^3 + 180*x^2 - 40*x + 5)
 
gp: K = bnfinit(x^16 - 8*x^15 + 40*x^14 - 140*x^13 + 386*x^12 - 860*x^11 + 1576*x^10 - 2380*x^9 + 3001*x^8 - 3180*x^7 + 2820*x^6 - 2052*x^5 + 1196*x^4 - 540*x^3 + 180*x^2 - 40*x + 5, 1)
 

Normalized defining polynomial

\( x^{16} - 8 x^{15} + 40 x^{14} - 140 x^{13} + 386 x^{12} - 860 x^{11} + 1576 x^{10} - 2380 x^{9} + 3001 x^{8} - 3180 x^{7} + 2820 x^{6} - 2052 x^{5} + 1196 x^{4} - 540 x^{3} + 180 x^{2} - 40 x + 5 \)

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:  \(268435456000000000000=2^{40}\cdot 5^{12}\)
magma: Discriminant(Integers(K));
 
sage: K.disc()
 
gp: K.disc
 
Root discriminant:  $18.91$
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:  $2, 5$
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 \(a\))

$1$, $a$, $a^{2}$, $a^{3}$, $a^{4}$, $a^{5}$, $a^{6}$, $a^{7}$, $a^{8}$, $a^{9}$, $a^{10}$, $a^{11}$, $a^{12}$, $a^{13}$, $\frac{1}{2291} a^{14} - \frac{7}{2291} a^{13} - \frac{701}{2291} a^{12} - \frac{285}{2291} a^{11} - \frac{840}{2291} a^{10} - \frac{991}{2291} a^{9} + \frac{866}{2291} a^{8} - \frac{367}{2291} a^{7} - \frac{694}{2291} a^{6} - \frac{252}{2291} a^{5} + \frac{1071}{2291} a^{4} + \frac{707}{2291} a^{3} - \frac{689}{2291} a^{2} - \frac{110}{2291} a - \frac{515}{2291}$, $\frac{1}{460491} a^{15} + \frac{31}{153497} a^{14} + \frac{113149}{460491} a^{13} + \frac{36868}{153497} a^{12} + \frac{172268}{460491} a^{11} - \frac{188086}{460491} a^{10} - \frac{203620}{460491} a^{9} + \frac{20344}{153497} a^{8} + \frac{203161}{460491} a^{7} - \frac{49033}{460491} a^{6} - \frac{26420}{460491} a^{5} + \frac{204029}{460491} a^{4} - \frac{4155}{153497} a^{3} - \frac{76460}{153497} a^{2} - \frac{75623}{153497} a + \frac{214256}{460491}$

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

Class group and class number

$C_{2}$, which has order $2$

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:  \( \frac{152612}{460491} a^{15} - \frac{381530}{153497} a^{14} + \frac{5537210}{460491} a^{13} - \frac{6210750}{153497} a^{12} + \frac{49753510}{460491} a^{11} - \frac{106880708}{460491} a^{10} + \frac{188381050}{460491} a^{9} - \frac{90567785}{153497} a^{8} + \frac{326718830}{460491} a^{7} - \frac{328395830}{460491} a^{6} + \frac{274192850}{460491} a^{5} - \frac{184697555}{460491} a^{4} + \frac{32696550}{153497} a^{3} - \frac{13007600}{153497} a^{2} + \frac{3801300}{153497} a - \frac{1876262}{460491} \) (order $4$)
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:  \( 11020.5408569 \)
magma: Regulator(K);
 
sage: K.regulator()
 
gp: K.reg
 

Galois group

$C_2^2.D_4$ (as 16T33):

magma: GaloisGroup(K);
 
sage: K.galois_group(type='pari')
 
gp: polgalois(K.pol)
 
A solvable group of order 32
The 11 conjugacy class representatives for $C_2^2.D_4$
Character table for $C_2^2.D_4$

Intermediate fields

\(\Q(\sqrt{-1}) \), \(\Q(\sqrt{-5}) \), \(\Q(\sqrt{5}) \), 4.2.8000.1 x2, 4.0.32000.1 x2, \(\Q(i, \sqrt{5})\), 8.0.1024000000.6, 8.0.16384000000.3 x2, 8.0.204800000.3 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 ${\href{/LocalNumberField/3.4.0.1}{4} }^{2}{,}\,{\href{/LocalNumberField/3.2.0.1}{2} }^{4}$ R ${\href{/LocalNumberField/7.4.0.1}{4} }^{2}{,}\,{\href{/LocalNumberField/7.2.0.1}{2} }^{4}$ ${\href{/LocalNumberField/11.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/13.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/17.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/19.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/23.4.0.1}{4} }^{2}{,}\,{\href{/LocalNumberField/23.2.0.1}{2} }^{4}$ ${\href{/LocalNumberField/29.2.0.1}{2} }^{4}{,}\,{\href{/LocalNumberField/29.1.0.1}{1} }^{8}$ ${\href{/LocalNumberField/31.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/37.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/41.2.0.1}{2} }^{8}$ ${\href{/LocalNumberField/43.4.0.1}{4} }^{2}{,}\,{\href{/LocalNumberField/43.2.0.1}{2} }^{4}$ ${\href{/LocalNumberField/47.4.0.1}{4} }^{2}{,}\,{\href{/LocalNumberField/47.2.0.1}{2} }^{4}$ ${\href{/LocalNumberField/53.4.0.1}{4} }^{4}$ ${\href{/LocalNumberField/59.2.0.1}{2} }^{8}$

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
2Data not computed
$5$5.4.3.2$x^{4} - 20$$4$$1$$3$$C_4$$[\ ]_{4}$
5.4.3.2$x^{4} - 20$$4$$1$$3$$C_4$$[\ ]_{4}$
5.4.3.2$x^{4} - 20$$4$$1$$3$$C_4$$[\ ]_{4}$
5.4.3.2$x^{4} - 20$$4$$1$$3$$C_4$$[\ ]_{4}$