Normalized defining polynomial
sage: x = polygen(QQ); K.<a> = NumberField(x^31 - 2)
gp: K = bnfinit(y^31 - 2, 1)
magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(x^31 - 2);
oscar: Qx, x = PolynomialRing(QQ); K, a = NumberField(x^31 - 2)
\( x^{31} - 2 \)
sage: K.defining_polynomial()
gp: K.pol
magma: DefiningPolynomial(K);
oscar: defining_polynomial(K)
Invariants
| Degree: | $31$ | sage: K.degree()
gp: poldegree(K.pol)
magma: Degree(K);
oscar: degree(K)
| |
| Signature: | $[1, 15]$ | sage: K.signature()
gp: K.sign
magma: Signature(K);
oscar: signature(K)
| |
| Discriminant: |
\(-18327886165296381817380980351835033630345588173537542144\)
\(\medspace = -\,2^{30}\cdot 31^{31}\)
| sage: K.disc()
gp: K.disc
magma: OK := Integers(K); Discriminant(OK);
oscar: OK = ring_of_integers(K); discriminant(OK)
| |
| Root discriminant: | \(60.63\) | sage: (K.disc().abs())^(1./K.degree())
gp: abs(K.disc)^(1/poldegree(K.pol))
magma: Abs(Discriminant(OK))^(1/Degree(K));
oscar: (1.0 * dK)^(1/degree(K))
| |
| Galois root discriminant: | $2^{30/31}31^{959/930}\approx 67.48167773073806$ | ||
| Ramified primes: |
\(2\), \(31\)
| sage: K.disc().support()
gp: factor(abs(K.disc))[,1]~
magma: PrimeDivisors(Discriminant(OK));
oscar: prime_divisors(discriminant((OK)))
| |
| Discriminant root field: | \(\Q(\sqrt{-31}) \) | ||
| $\card{ \Aut(K/\Q) }$: | $1$ | sage: K.automorphisms()
magma: Automorphisms(K);
oscar: automorphisms(K)
| |
| This field is not Galois over $\Q$. | |||
| This is not a CM field. | |||
Integral basis (with respect to field generator \(a\))
$1$, $a$, $a^{2}$, $a^{3}$, $a^{4}$, $a^{5}$, $a^{6}$, $a^{7}$, $a^{8}$, $a^{9}$, $a^{10}$, $a^{11}$, $a^{12}$, $a^{13}$, $a^{14}$, $a^{15}$, $a^{16}$, $a^{17}$, $a^{18}$, $a^{19}$, $a^{20}$, $a^{21}$, $a^{22}$, $a^{23}$, $a^{24}$, $a^{25}$, $a^{26}$, $a^{27}$, $a^{28}$, $a^{29}$, $a^{30}$
sage: K.integral_basis()
gp: K.zk
magma: IntegralBasis(K);
oscar: basis(OK)
| Monogenic: | Yes | |
| Index: | $1$ | |
| Inessential primes: | None |
Class group and class number
Trivial group, which has order $1$ (assuming GRH)
sage: K.class_group().invariants()
gp: K.clgp
magma: ClassGroup(K);
oscar: class_group(K)
Unit group
sage: UK = K.unit_group()
magma: UK, fUK := UnitGroup(K);
oscar: UK, fUK = unit_group(OK)
| Rank: | $15$ | sage: UK.rank()
gp: K.fu
magma: UnitRank(K);
oscar: rank(UK)
| |
| Torsion generator: |
\( -1 \)
(order $2$)
| sage: UK.torsion_generator()
gp: K.tu[2]
magma: K!f(TU.1) where TU,f is TorsionUnitGroup(K);
oscar: torsion_units_generator(OK)
| |
| Fundamental units: |
$a-1$, $a^{16}-a-1$, $a^{17}+a^{16}-a^{2}-a-1$, $a^{29}+a^{27}+a^{25}+a^{23}+a^{21}+a^{19}+a^{17}+a^{15}+a^{13}+a^{11}+a^{9}+a^{7}+a^{5}+a^{3}+a+1$, $a^{29}-a^{27}+a^{25}-a^{23}+a^{21}-a^{19}-a^{14}+a^{12}-a^{10}+a^{8}-a^{6}+a^{4}+a-1$, $a^{29}+a^{26}-a^{25}-a^{22}-a^{16}-a^{14}-a^{11}+a^{10}+a^{7}-a^{5}+2a^{4}+2a-1$, $a^{12}+a^{11}+a^{10}+a^{9}+a^{8}+a^{7}-a^{5}-a^{4}-a^{3}-a^{2}-2a-1$, $a^{30}+a^{28}-a^{25}+a^{22}-a^{19}-a^{18}+a^{16}+a^{15}+a^{14}+a^{13}-a^{12}-a^{11}-2a^{10}-a^{9}+2a^{7}+2a^{6}+2a^{5}-a^{4}-a^{3}-2a^{2}-a-1$, $a^{30}-a^{28}-a^{27}-a^{26}+a^{25}-a^{22}+a^{21}+a^{20}+2a^{19}+2a^{14}-2a^{13}-a^{12}-2a^{11}-a^{7}-a^{6}+a^{5}+2a^{4}+2a^{3}-2a^{2}+a-1$, $a^{30}+a^{29}+2a^{24}+3a^{23}+a^{22}+a^{20}-a^{18}+a^{16}+a^{15}+a^{14}-a^{13}-3a^{12}-2a^{11}-a^{10}-a^{9}-a^{8}-a^{5}-3a^{4}-3a^{3}+a+1$, $a^{30}-a^{29}-a^{28}-3a^{26}-2a^{25}+4a^{24}+2a^{23}+2a^{21}+a^{20}-2a^{19}-a^{18}-4a^{17}-5a^{16}+2a^{15}+2a^{14}-a^{13}+3a^{12}+6a^{11}+a^{10}+a^{9}-a^{8}-5a^{7}-a^{6}-5a^{4}-a^{3}+7a^{2}+2a+1$, $4a^{30}-3a^{28}-3a^{27}-3a^{26}+a^{25}+4a^{24}+4a^{23}+3a^{22}-5a^{20}-4a^{19}-3a^{18}+5a^{16}+4a^{15}+a^{14}-2a^{13}-6a^{12}-6a^{11}-a^{10}+a^{9}+6a^{8}+6a^{7}+a^{6}-2a^{5}-6a^{4}-7a^{3}+5a+7$, $a^{29}-a^{28}-a^{25}+2a^{24}-a^{23}-2a^{20}+3a^{19}-a^{18}-2a^{15}+3a^{14}-a^{13}-2a^{10}+2a^{9}-2a^{5}+a^{4}+a^{3}-a^{2}-1$, $a^{28}+a^{27}-a^{24}-2a^{23}-a^{22}+a^{21}+a^{20}+a^{19}+a^{18}+2a^{17}+2a^{16}+a^{15}-3a^{14}-4a^{13}-2a^{12}-a^{10}+a^{8}+3a^{7}+4a^{6}+2a^{5}-2a^{4}-a^{3}-a^{2}-2a-1$, $2a^{30}-2a^{29}+a^{27}+2a^{25}-2a^{24}+2a^{22}-a^{21}+a^{20}-2a^{19}+3a^{17}-2a^{16}+a^{15}+3a^{12}-4a^{11}-a^{10}+a^{9}-2a^{8}+2a^{7}-3a^{6}+4a^{4}-3a^{3}-2a-1$
| sage: UK.fundamental_units()
gp: K.fu
magma: [K|fUK(g): g in Generators(UK)];
oscar: [K(fUK(a)) for a in gens(UK)]
| |
| Regulator: | \( 5190129910021260.0 \) (assuming GRH) | sage: K.regulator()
gp: K.reg
magma: Regulator(K);
oscar: regulator(K)
|
Class number formula
\[ \begin{aligned}\lim_{s\to 1} (s-1)\zeta_K(s) =\mathstrut & \frac{2^{r_1}\cdot (2\pi)^{r_2}\cdot R\cdot h}{w\cdot\sqrt{|D|}}\cr \approx\mathstrut &\frac{2^{1}\cdot(2\pi)^{15}\cdot 5190129910021260.0 \cdot 1}{2\cdot\sqrt{18327886165296381817380980351835033630345588173537542144}}\cr\approx \mathstrut & 1.13846599841673 \end{aligned}\] (assuming GRH)
# self-contained SageMath code snippet to compute the analytic class number formula
x = polygen(QQ); K.<a> = NumberField(x^31 - 2)
DK = K.disc(); r1,r2 = K.signature(); RK = K.regulator(); RR = RK.parent()
hK = K.class_number(); wK = K.unit_group().torsion_generator().order();
2^r1 * (2*RR(pi))^r2 * RK * hK / (wK * RR(sqrt(abs(DK))))
# self-contained Pari/GP code snippet to compute the analytic class number formula
K = bnfinit(x^31 - 2, 1);
[polcoeff (lfunrootres (lfuncreate (K))[1][1][2], -1), 2^K.r1 * (2*Pi)^K.r2 * K.reg * K.no / (K.tu[1] * sqrt (abs (K.disc)))]
/* self-contained Magma code snippet to compute the analytic class number formula */
Qx<x> := PolynomialRing(QQ); K<a> := NumberField(x^31 - 2);
OK := Integers(K); DK := Discriminant(OK);
UK, fUK := UnitGroup(OK); clK, fclK := ClassGroup(OK);
r1,r2 := Signature(K); RK := Regulator(K); RR := Parent(RK);
hK := #clK; wK := #TorsionSubgroup(UK);
2^r1 * (2*Pi(RR))^r2 * RK * hK / (wK * Sqrt(RR!Abs(DK)));
# self-contained Oscar code snippet to compute the analytic class number formula
Qx, x = PolynomialRing(QQ); K, a = NumberField(x^31 - 2);
OK = ring_of_integers(K); DK = discriminant(OK);
UK, fUK = unit_group(OK); clK, fclK = class_group(OK);
r1,r2 = signature(K); RK = regulator(K); RR = parent(RK);
hK = order(clK); wK = torsion_units_order(K);
2^r1 * (2*pi)^r2 * RK * hK / (wK * sqrt(RR(abs(DK))))
Galois group
sage: K.galois_group(type='pari')
gp: polgalois(K.pol)
magma: G = GaloisGroup(K);
oscar: G, Gtx = galois_group(K); G, transitive_group_identification(G)
| A solvable group of order 930 |
| The 31 conjugacy class representatives for $F_{31}$ |
| Character table for $F_{31}$ is not computed |
Intermediate fields
| The extension is primitive: there are no intermediate fields between this field and $\Q$. |
sage: K.subfields()[1:-1]
gp: L = nfsubfields(K); L[2..length(b)]
magma: L := Subfields(K); L[2..#L];
oscar: subfields(K)[2:end-1]
Frobenius cycle types
| $p$ | $2$ | $3$ | $5$ | $7$ | $11$ | $13$ | $17$ | $19$ | $23$ | $29$ | $31$ | $37$ | $41$ | $43$ | $47$ | $53$ | $59$ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cycle type | R | $30{,}\,{\href{/padicField/3.1.0.1}{1} }$ | ${\href{/padicField/5.3.0.1}{3} }^{10}{,}\,{\href{/padicField/5.1.0.1}{1} }$ | $15^{2}{,}\,{\href{/padicField/7.1.0.1}{1} }$ | $30{,}\,{\href{/padicField/11.1.0.1}{1} }$ | $30{,}\,{\href{/padicField/13.1.0.1}{1} }$ | $30{,}\,{\href{/padicField/17.1.0.1}{1} }$ | $15^{2}{,}\,{\href{/padicField/19.1.0.1}{1} }$ | ${\href{/padicField/23.10.0.1}{10} }^{3}{,}\,{\href{/padicField/23.1.0.1}{1} }$ | ${\href{/padicField/29.10.0.1}{10} }^{3}{,}\,{\href{/padicField/29.1.0.1}{1} }$ | R | ${\href{/padicField/37.6.0.1}{6} }^{5}{,}\,{\href{/padicField/37.1.0.1}{1} }$ | $15^{2}{,}\,{\href{/padicField/41.1.0.1}{1} }$ | $30{,}\,{\href{/padicField/43.1.0.1}{1} }$ | ${\href{/padicField/47.5.0.1}{5} }^{6}{,}\,{\href{/padicField/47.1.0.1}{1} }$ | $30{,}\,{\href{/padicField/53.1.0.1}{1} }$ | $15^{2}{,}\,{\href{/padicField/59.1.0.1}{1} }$ |
In the table, R denotes a ramified prime. Cycle lengths which are repeated in a cycle type are indicated by exponents.
# to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7$ in Sage:
p = 7; [(e, pr.norm().valuation(p)) for pr,e in K.factor(p)]
\\ to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7$ in Pari:
p = 7; pfac = idealprimedec(K, p); vector(length(pfac), j, [pfac[j][3], pfac[j][4]])
// to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7 in Magma:
p := 7; [<pr[2], Valuation(Norm(pr[1]), p)> : pr in Factorization(p*Integers(K))];
# to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7$ in Oscar:
p = 7; pfac = factor(ideal(ring_of_integers(K), p)); [(e, valuation(norm(pr),p)) for (pr,e) in pfac]
Local algebras for ramified primes
| $p$ | Label | Polynomial | $e$ | $f$ | $c$ | Galois group | Slope content |
|---|---|---|---|---|---|---|---|
|
\(2\)
| Deg $31$ | $31$ | $1$ | $30$ | |||
|
\(31\)
| Deg $31$ | $31$ | $1$ | $31$ |