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Structure Operations

Structure Operations

In the lists below, K denotes a quadratic field, O a quadratic order, and B a magma of binary quadratic forms.

Subsections

Related Structures

Category(K) : FldQuad -> Cat
Category(O) : RngQuad -> Cat
Category(B) : MagForm -> Cat
Parent(K) : FldQuad -> Pow
Parent(O) : RngQuad -> Pow
Parent(B) : MagForm -> Pow
PrimeField(K) : FldQuad -> FldRat
PrimeRing(O) : RngQuad -> RngInt

Basis

IntegralBasis(K) : FldQuad -> [ FldQuadElt ]
This function returns a sequence of elements of the quadratic field K that form an integral basis for K.
Basis(O) : RngQuad -> [ FldQuadElt ]
A Z-basis for the order O, as a sequence of two elements of the quadratic field K in which O is contained. The two elements are 1 and f omega , where 1, omega form the standard integral basis for K, and f is the conductor of O.

Ideal Class Group

ClassGroup(K) : FldQuad -> GrpAb
ClassGroup(O) : RngQuad -> GrpAb
The class group of an order O or the maximal order of the quadratic field K, as an abelian group. The function also returns a map between the group and the magma of quadratic forms of the associated discriminant.
ClassGroupStructure(K) : FldQuad -> [ RngIntElt ]
ClassGroupStructure(O) : RngQuad -> [ RngIntElt ]
The structure of the class group of the order O or the maximal order of the quadratic field K, as a sequence of integers giving the abelian invariants.
ClassNumber(K) : FldQuad -> RngIntElt
ClassNumber(O) : RngQuad -> RngIntElt
The class number of O or the order O or the maximal order of the quadratic field K.

Unit Group

UnitGroup(K) : FldQuad -> GrpAb, Map
UnitGroup(O) : RngQuad -> GrpAb, Map
The unit group of the order O or the maximal order of the quadratic field K, as an abelian group, together with a map to the order (or field).
TorsionSubgroup(K) : FldQuad -> GrpAb, Map
TorsionSubgroup(O) : RngQuad -> GrpAb, Map
Returns the torsion part of the unit group of the order O or of the maximal order of the quadratic field K, as a finite abelian group together with a map from the group to the order O or the field K.
FundamentalUnit(K) : FldQuad -> FldQuadElt
FundamentalUnit(O) : RngQuad -> RngQuadElt
A generator for the unit group of the order O or the maximal order of the quadratic field K.
UnitRank(K) : FldQuad -> RngIntElt
UnitRank(O) : RngQuad -> RngIntElt
The rank of the free part of the unit group of the order O or the maximal order of the quadratic field K, which equals 1 for real quadratic fields and 0 for imagnary quadratic fields.

Numerical Invariants

Characteristic(K) : FldQuad -> RngIntElt
Characteristic(O) : RngQuad -> RngIntElt
Degree(K) : FldQuad -> RngIntElt
Degree(O) : RngQuad -> RngIntElt
The (absolute) degree of K over Q, or of the order O (as a Z-module), which is 2 for all quadratic fields and orders.
Discriminant(K) : FldQuad -> RngIntElt
Discriminant(O) : FldQuad -> RngIntElt
The discriminant of the quadratic field K or of an order O of K. If K=Q(sqrt(d)), with d squarefree, this returns d if d = 0, 1 mod 4, and 4d otherwise. For the order the discriminant equals f^2 times the field discriminant, where f is the index of O in the maximal order.
Conductor(K) : FldQuad -> RngIntElt
The finite part of the conductor of the quadratic field K. This is the smallest positive integer n such that K is contained in Q(zeta_n). It equals the absolute value of the discriminant.
Conductor(O) : RngQuad -> RngIntElt
The conductor of order O, which equals the index of O in the ring of integers of its field of fractions.
Regulator(K) : FldQuad -> RngIntElt
Regulator(O) : RngQuad -> RngIntElt
The regulator of the order O or the maximal order of the quadratic field K.
Signature(K) : FldQuad -> RngIntElt
The signature of the quadratic field, that is, the number of real embeddings and the number of pairs of complex embeddings of K. So this function returns either 2, 0 or 0, 1 depending on whether the field is real or imaginary quadratic.

Predicates and Boolean Operators

The predicates listed below are available both for quadratic fields and for their orders.

IsCommutative(K) : FldQuad -> BoolElt
IsCommutative(O) : RngQuad -> BoolElt
IsUnitary(K) : FldQuad -> BoolElt
IsUnitary(O) : RngQuad -> BoolElt
IsFinite(K) : FldQuad -> BoolElt
IsOrdered(K) : FldQuad -> BoolElt
IsFinite(O) : RngQuad -> BoolElt
IsOrdered(O) : RngQuad -> BoolElt
IsField(K) : FldQuad -> BoolElt
IsEuclideanDomain(K) : FldQuad -> BoolElt
IsField(O) : RngQuad -> BoolElt
IsEuclideanDomain(O) : RngQuad -> BoolElt
IsPID(K) : FldQuad -> BoolElt
IsUFD(K) : FldQuad -> BoolElt
IsPID(O) : RngQuad -> BoolElt
IsUFD(O) : RngQuad -> BoolElt
IsDivisionRing(K) : FldQuad -> BoolElt
IsEuclideanRing(K) : FldQuad -> BoolElt
IsDivisionRing(O) : RngQuad -> BoolElt
IsEuclideanRing(O) : RngQuad -> BoolElt
IsPrincipalIdealRing(K) : FldQuad -> BoolElt
IsDomain(K) : FldQuad -> BoolElt
IsPrincipalIdealRing(O) : RngQuad -> BoolElt
IsDomain(O) : RngQuad -> BoolElt
K eq L : FldQuad, FldQuad -> BoolElt
O eq P : RngQuad, RngQuad -> BoolElt
K ne L : FldQuad, FldQuad -> BoolElt
O ne P : RngQuad, RngQuad -> BoolElt
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