NumberField( gens )
NumberField( n, stab )
NumberField( subfield, poly )
NumberField( subfield, base )
NumberField
may be abbreviated NF
; it returns number fields, namely
NumberField( gens )
:
the number field generated by the cyclotomics in the list gens,
NumberField( n, stab )
:
the fixed field of the prime residues in the list stab inside the
cyclotomic field Q_n (see Cyclotomic Field Records),
NumberField( subfield, poly )
:
the splitting field of the polynomial poly (which must have degree
at most 2) over the number field subfield; subfield = 0
is equivalent to subfield = Rationals
,
NumberField( subfield, base )
:
the extension field of the number field subfield which is
as vector space generated by the elements of the list base of
cyclotomics; that means, base must be or at least contain a vector
space base of this extension, if base is a base it will be
assigned to the base
field of the cyclotomic field
(see Coefficients for Number Fields).
subfield = 0
is equivalent to subfield = Rationals
.
gap> NF( [ EB(7), ER(3) ] ); NF(84,[ 1, 11, 23, 25, 37, 71 ]) gap> NF( 7, [ 1 ] ); CF(7) gap> NF( NF( [ EB(7) ] ), [ 1, 1, 1 ] ); NF(NF(7,[ 1, 2, 4 ]),[ 1, E(3) ]) gap> F:= NF( 0, [ 1, E(4) ] ); G:= NF( 0, NormalBaseNumberField( F ) ); GaussianRationals CF( Rationals,[ 1/2-1/2*E(4), 1/2+1/2*E(4) ]) gap> G.base; G.basechangemat; Coefficients( G, 1 ); [ 1/2-1/2*E(4), 1/2+1/2*E(4) ] [ [ 1, 1 ], [ -1, 1 ] ] [ 1, 1 ]
Number field records are field records (see Field Records) representing a number field. Besides the obligatory record components, a number field record F contains the component
stabilizer
:NofCyc( F.generators )
which
fix all elements of F
and possibly
isIntegralBase
:true
if F.base
is an integral vector space base of the field
extension F / F.field
, false
else (used by Ring Ring
);
for the case that F.field
is a cyclotomic field,
Integral Bases for Number Fields describes integral bases of the
field extension;
isNormalBase
:true
if F.base
is a normal vector space base of the field
extension F/F.field
, false
else;
coeffslist
:Coefficients
; (see also
Coefficients for Number Fields);
coeffsmat
:Coefficients
;
bound only if F.field
is not a cyclotomic field
(see also Coefficients for Number Fields);
basechangemat
:F.dimension
, representing the
basechange from the default base of F / F.field
(see Coefficients for Number Fields) to the base stored
in F.base
if these two are different; used by Coefficients
.
Note: These fields and also the field base
should not be changed by
hand!
GAP 3.4.4