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Properties

Label 18.0.62325088634...0963.1
Degree $18$
Signature $[0, 9]$
Discriminant $-\,3^{37}\cdot 7^{12}$
Root discriminant $35.01$
Ramified primes $3, 7$
Class number $12$ (GRH)
Class group $[2, 6]$ (GRH)
Galois group $C_3^2 : C_2$ (as 18T4)

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Show commands for: Magma / SageMath / Pari/GP

magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(R![1728, 0, 0, 0, 0, 0, 8937, 0, 0, 0, 0, 0, -90, 0, 0, 0, 0, 0, 1]);
 
sage: x = polygen(QQ); K.<a> = NumberField(x^18 - 90*x^12 + 8937*x^6 + 1728)
 
gp: K = bnfinit(x^18 - 90*x^12 + 8937*x^6 + 1728, 1)
 

Normalized defining polynomial

\( x^{18} - 90 x^{12} + 8937 x^{6} + 1728 \)

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

Invariants

Degree:  $18$
magma: Degree(K);
 
sage: K.degree()
 
gp: poldegree(K.pol)
 
Signature:  $[0, 9]$
magma: Signature(K);
 
sage: K.signature()
 
gp: K.sign
 
Discriminant:  \(-6232508863425350301616650963=-\,3^{37}\cdot 7^{12}\)
magma: Discriminant(Integers(K));
 
sage: K.disc()
 
gp: K.disc
 
Root discriminant:  $35.01$
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:  $3, 7$
magma: PrimeDivisors(Discriminant(Integers(K)));
 
sage: K.disc().support()
 
gp: factor(abs(K.disc))[,1]~
 
This field is Galois over $\Q$.
This is not a CM field.

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

$1$, $a$, $a^{2}$, $a^{3}$, $\frac{1}{2} a^{4} - \frac{1}{2} a$, $\frac{1}{2} a^{5} - \frac{1}{2} a^{2}$, $\frac{1}{6} a^{6} - \frac{1}{2} a^{3}$, $\frac{1}{6} a^{7} - \frac{1}{2} a$, $\frac{1}{12} a^{8} + \frac{1}{4} a^{2}$, $\frac{1}{48} a^{9} + \frac{1}{16} a^{3} - \frac{1}{2}$, $\frac{1}{144} a^{10} + \frac{1}{48} a^{4} - \frac{1}{2} a$, $\frac{1}{144} a^{11} + \frac{1}{48} a^{5} - \frac{1}{2} a^{2}$, $\frac{1}{13680} a^{12} + \frac{193}{4560} a^{6} - \frac{1}{2} a^{3} - \frac{3}{95}$, $\frac{1}{82080} a^{13} - \frac{1}{288} a^{10} + \frac{1}{144} a^{9} - \frac{1327}{27360} a^{7} - \frac{1}{6} a^{5} + \frac{23}{96} a^{4} + \frac{1}{48} a^{3} - \frac{1}{2} a^{2} + \frac{89}{1140} a - \frac{1}{2}$, $\frac{1}{82080} a^{14} - \frac{1}{288} a^{11} + \frac{953}{27360} a^{8} + \frac{23}{96} a^{5} + \frac{187}{570} a^{2}$, $\frac{1}{82080} a^{15} - \frac{1}{27360} a^{12} - \frac{187}{27360} a^{9} + \frac{189}{3040} a^{6} + \frac{463}{2280} a^{3} - \frac{46}{95}$, $\frac{1}{82080} a^{16} - \frac{23}{6840} a^{10} - \frac{1}{12} a^{7} - \frac{111}{3040} a^{4} - \frac{1}{4} a$, $\frac{1}{164160} a^{17} + \frac{49}{27360} a^{11} - \frac{1}{24} a^{8} + \frac{4417}{18240} a^{5} + \frac{3}{8} a^{2}$

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

Class group and class number

$C_{2}\times C_{6}$, which has order $12$ (assuming GRH)

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

Unit group

magma: UK, f := UnitGroup(K);
 
sage: UK = K.unit_group()
 
Rank:  $8$
magma: UnitRank(K);
 
sage: UK.rank()
 
gp: K.fu
 
Torsion generator:  \( -\frac{1}{4560} a^{15} + \frac{43}{2280} a^{9} - \frac{2991}{1520} a^{3} + \frac{1}{2} \) (order $6$)
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 (assuming GRH)
magma: [K!f(g): g in Generators(UK)];
 
sage: UK.fundamental_units()
 
gp: K.fu
 
Regulator:  \( 10060033.1251 \) (assuming GRH)
magma: Regulator(K);
 
sage: K.regulator()
 
gp: K.reg
 

Galois group

$C_3:S_3$ (as 18T4):

magma: GaloisGroup(K);
 
sage: K.galois_group(type='pari')
 
gp: polgalois(K.pol)
 
A solvable group of order 18
The 6 conjugacy class representatives for $C_3^2 : C_2$
Character table for $C_3^2 : C_2$

Intermediate fields

\(\Q(\sqrt{-3}) \), 3.1.11907.1 x3, 3.1.243.1 x3, 3.1.1323.1 x3, 3.1.11907.2 x3, 6.0.425329947.3, 6.0.177147.2, 6.0.5250987.1, 6.0.425329947.5, 9.1.45579633110361.5 x9

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

Sibling fields

Degree 9 sibling: 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 ${\href{/LocalNumberField/2.2.0.1}{2} }^{9}$ R ${\href{/LocalNumberField/5.2.0.1}{2} }^{9}$ R ${\href{/LocalNumberField/11.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/13.3.0.1}{3} }^{6}$ ${\href{/LocalNumberField/17.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/19.3.0.1}{3} }^{6}$ ${\href{/LocalNumberField/23.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/29.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/31.3.0.1}{3} }^{6}$ ${\href{/LocalNumberField/37.3.0.1}{3} }^{6}$ ${\href{/LocalNumberField/41.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/43.3.0.1}{3} }^{6}$ ${\href{/LocalNumberField/47.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/53.2.0.1}{2} }^{9}$ ${\href{/LocalNumberField/59.2.0.1}{2} }^{9}$

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
3Data not computed
$7$7.9.6.1$x^{9} + 42 x^{6} + 539 x^{3} + 2744$$3$$3$$6$$C_3^2$$[\ ]_{3}^{3}$
7.9.6.1$x^{9} + 42 x^{6} + 539 x^{3} + 2744$$3$$3$$6$$C_3^2$$[\ ]_{3}^{3}$