|
#############################################################################
##
## This file is part of GAP, a system for computational discrete algebra.
## This file's authors include Frank Celler, Alexander Hulpke.
##
## Copyright of GAP belongs to its developers, whose names are too numerous
## to list here. Please refer to the COPYRIGHT file for details.
##
## SPDX-License-Identifier: GPL-2.0-or-later
##
## This file contains the categories, attributes, properties and operations
## for rational functions, Laurent polynomials and polynomials and their
## families.
## Warning:
## If the mechanism for storing attributes is changed,
## `LaurentPolynomialByExtRep' must be changed as well.
## Also setter methods for coefficients and/or indeterminate number will be
## ignored when creating Laurent polynomials.
## (This is ugly and inconsistent, but crucial to get speed. ahulpke, May99)
#############################################################################
##
#I InfoPoly
##
## <#GAPDoc Label="InfoPoly">
## <ManSection>
## <InfoClass Name="InfoPoly"/>
##
## <Description>
## is the info class for univariate polynomials.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareInfoClass( "InfoPoly" );
#############################################################################
##
#C IsPolynomialFunction(<obj>)
#C IsRationalFunction(<obj>)
##
## <#GAPDoc Label="IsPolynomialFunction">
## <ManSection>
## <Filt Name="IsPolynomialFunction" Arg='obj' Type='Category'/>
## <Filt Name="IsRationalFunction" Arg='obj' Type='Category'/>
##
## <Description>
## A rational function is an element of the quotient field of a polynomial
## ring over an UFD. It is represented as a quotient of two polynomials,
## its numerator (see <Ref Attr="NumeratorOfRationalFunction"/>) and
## its denominator (see <Ref Attr="DenominatorOfRationalFunction"/>)
## <P/>
## A polynomial function is an element of a polynomial ring (not
## necessarily an UFD), or a rational function.
## <P/>
## &GAP; considers <Ref Filt="IsRationalFunction"/> as a subcategory of
## <Ref Filt="IsPolynomialFunction"/>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareCategory( "IsPolynomialFunction", IsRingElementWithInverse and IsZDFRE);
DeclareCategory( "IsRationalFunction", IsPolynomialFunction);
DeclareCategoryCollections( "IsPolynomialFunction" );
DeclareCategoryCollections( "IsRationalFunction" );
#############################################################################
##
#C IsPolynomialFunctionsFamilyElement(<obj>)
#C IsRationalFunctionsFamilyElement(<obj>)
##
## <ManSection>
## <Filt Name="IsPolynomialFunctionsFamilyElement" Arg='obj' Type='Category'/>
## <Filt Name="IsRationalFunctionsFamilyElement" Arg='obj' Type='Category'/>
##
## <Description>
## A polynomial is an element of a polynomial functions family. If the
## underlying domain is an UFD, it is even a
## <Ref Func="IsRationalFunctionsFamilyElement"/>.
## </Description>
## </ManSection>
##
DeclareCategory("IsPolynomialFunctionsFamilyElement",IsPolynomialFunction);
DeclareCategory("IsRationalFunctionsFamilyElement",
IsRationalFunction and IsPolynomialFunctionsFamilyElement );
#############################################################################
##
#C IsPolynomialFunctionsFamily(<obj>)
#C IsRationalFunctionsFamily(<obj>)
##
## <#GAPDoc Label="IsPolynomialFunctionsFamily">
## <ManSection>
## <Filt Name="IsPolynomialFunctionsFamily" Arg='obj' Type='Category'/>
## <Filt Name="IsRationalFunctionsFamily" Arg='obj' Type='Category'/>
##
## <Description>
## <Ref Filt="IsPolynomialFunctionsFamily"/> is the category of a family of
## polynomials.
## For families over an UFD, the category becomes
## <Ref Filt="IsRationalFunctionsFamily"/> (as rational functions and
## quotients are only provided for families over an UFD.)
## <!-- 1996/10/14 fceller can this be done with <C>CategoryFamily</C>?-->
## <P/>
## <Log><![CDATA[
## gap> fam:=RationalFunctionsFamily(FamilyObj(1));
## NewFamily( "RationalFunctionsFamily(...)", [ 618, 620 ],
## [ 82, 85, 89, 93, 97, 100, 103, 107, 111, 618, 620 ] )
## ]]></Log>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareCategory( "IsPolynomialFunctionsFamily", IsFamily );
DeclareCategory( "IsRationalFunctionsFamily", IsPolynomialFunctionsFamily and IsUFDFamily );
#############################################################################
##
#C IsRationalFunctionOverField(<obj>)
##
## <ManSection>
## <Filt Name="IsRationalFunctionOverField" Arg='obj' Type='Category'/>
##
## <Description>
## Indicates that the coefficients family for the rational function <A>obj</A>
## is a field. In this situation it is permissible to move coefficients
## from the denominator in the numerator, in particular the quotient of a
## polynomial by a coefficient is again a polynomial. This last property
## does not necessarily hold for polynomials over arbitrary rings.
## </Description>
## </ManSection>
##
DeclareCategory("IsRationalFunctionOverField", IsRationalFunction );
#############################################################################
##
#A RationalFunctionsFamily( <fam> )
##
## <#GAPDoc Label="RationalFunctionsFamily">
## <ManSection>
## <Attr Name="RationalFunctionsFamily" Arg='fam'/>
##
## <Description>
## creates a family containing rational functions with coefficients
## in <A>fam</A>.
## All elements of the <Ref Attr="RationalFunctionsFamily"/> are
## rational functions (see <Ref Filt="IsRationalFunction"/>).
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "RationalFunctionsFamily", IsFamily );
#############################################################################
##
#A CoefficientsFamily( <rffam> )
##
## <#GAPDoc Label="CoefficientsFamily">
## <ManSection>
## <Attr Name="CoefficientsFamily" Arg='rffam'/>
##
## <Description>
## If <A>rffam</A> has been created as
## <C>RationalFunctionsFamily(<A>cfam</A>)</C> this attribute holds the
## coefficients family <A>cfam</A>.
## <P/>
## &GAP; does <E>not</E> embed the base ring in the polynomial ring. While
## multiplication and addition of base ring elements to rational functions
## return the expected results, polynomials and rational functions are not
## equal.
## <Example><![CDATA[
## gap> 1=Indeterminate(Rationals)^0;
## false
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "CoefficientsFamily", IsFamily );
#############################################################################
##
#A NumeratorOfRationalFunction( <ratfun> )
##
## <#GAPDoc Label="NumeratorOfRationalFunction">
## <ManSection>
## <Attr Name="NumeratorOfRationalFunction" Arg='ratfun'/>
##
## <Description>
## returns the numerator of the rational function <A>ratfun</A>.
## <P/>
## As no proper multivariate gcd has been implemented yet, numerators and
## denominators are not guaranteed to be reduced!
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "NumeratorOfRationalFunction", IsPolynomialFunction);
#############################################################################
##
#A DenominatorOfRationalFunction( <ratfun> )
##
## <#GAPDoc Label="DenominatorOfRationalFunction">
## <ManSection>
## <Attr Name="DenominatorOfRationalFunction" Arg='ratfun'/>
##
## <Description>
## returns the denominator of the rational function <A>ratfun</A>.
## <P/>
## As no proper multivariate gcd has been implemented yet, numerators and
## denominators are not guaranteed to be reduced!
## <Example><![CDATA[
## gap> x:=Indeterminate(Rationals,1);;y:=Indeterminate(Rationals,2);;
## gap> DenominatorOfRationalFunction((x*y+x^2)/y);
## y
## gap> NumeratorOfRationalFunction((x*y+x^2)/y);
## x^2+x*y
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "DenominatorOfRationalFunction", IsRationalFunction );
#############################################################################
##
#P IsPolynomial( <ratfun> )
##
## <#GAPDoc Label="IsPolynomial">
## <ManSection>
## <Prop Name="IsPolynomial" Arg='ratfun'/>
##
## <Description>
## A polynomial is a rational function whose denominator is one. (If the
## coefficients family forms a field this is equivalent to the denominator
## being constant.)
## <P/>
## If the base family is not a field, it may be impossible to represent the
## quotient of a polynomial by a ring element as a polynomial again, but it
## will have to be represented as a rational function.
## <Example><![CDATA[
## gap> IsPolynomial((x*y+x^2*y^3)/y);
## true
## gap> IsPolynomial((x*y+x^2)/y);
## false
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareProperty( "IsPolynomial", IsPolynomialFunction );
InstallTrueMethod( IsPolynomialFunction, IsPolynomial );
#############################################################################
##
#A AsPolynomial( <poly> )
##
## <#GAPDoc Label="AsPolynomial">
## <ManSection>
## <Attr Name="AsPolynomial" Arg='poly'/>
##
## <Description>
## If <A>poly</A> is a rational function that is a polynomial this attribute
## returns an equal rational function <M>p</M> such that <M>p</M> is equal
## to its numerator and the denominator of <M>p</M> is one.
## <Example><![CDATA[
## gap> AsPolynomial((x*y+x^2*y^3)/y);
## x^2*y^2+x
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "AsPolynomial",
IsPolynomialFunction and IsPolynomial);
#############################################################################
##
#P IsUnivariateRationalFunction( <ratfun> )
##
## <#GAPDoc Label="IsUnivariateRationalFunction">
## <ManSection>
## <Prop Name="IsUnivariateRationalFunction" Arg='ratfun'/>
##
## <Description>
## A rational function is univariate if its numerator and its denominator
## are both polynomials in the same one indeterminate. The attribute
## <Ref Attr="IndeterminateNumberOfUnivariateRationalFunction"/> can be used to obtain
## the number of this common indeterminate.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareProperty( "IsUnivariateRationalFunction", IsRationalFunction );
InstallTrueMethod( IsRationalFunction, IsUnivariateRationalFunction );
#############################################################################
##
#P IsUnivariatePolynomial( <ratfun> )
##
## <#GAPDoc Label="IsUnivariatePolynomial">
## <ManSection>
## <Prop Name="IsUnivariatePolynomial" Arg='ratfun'/>
##
## <Description>
## A univariate polynomial is a polynomial in only one indeterminate.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareSynonymAttr("IsUnivariatePolynomial",
IsPolynomial and IsUnivariateRationalFunction);
#############################################################################
##
#P IsLaurentPolynomial( <ratfun> )
##
## <#GAPDoc Label="IsLaurentPolynomial">
## <ManSection>
## <Prop Name="IsLaurentPolynomial" Arg='ratfun'/>
##
## <Description>
## A Laurent polynomial is a univariate rational function whose denominator
## is a monomial. Therefore every univariate polynomial is a
## Laurent polynomial.
## <P/>
## The attribute <Ref Attr="CoefficientsOfLaurentPolynomial"/> gives a
## compact representation as Laurent polynomial.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareProperty( "IsLaurentPolynomial", IsPolynomialFunction );
InstallTrueMethod( IsUnivariateRationalFunction, IsLaurentPolynomial );
InstallTrueMethod( IsLaurentPolynomial, IsUnivariatePolynomial );
#############################################################################
##
#P IsConstantRationalFunction( <ratfun> )
##
## <#GAPDoc Label="IsConstantRationalFunction">
## <ManSection>
## <Prop Name="IsConstantRationalFunction" Arg='ratfun'/>
##
## <Description>
## A constant rational function is a function whose numerator and
## denominator are polynomials of degree 0.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareProperty( "IsConstantRationalFunction", IsPolynomialFunction );
InstallTrueMethod( IsUnivariateRationalFunction, IsConstantRationalFunction );
#############################################################################
##
#P IsZeroRationalFunction( <ratfun> )
##
## <ManSection>
## <Prop Name="IsZeroRationalFunction" Arg='ratfun'/>
##
## <Description>
## This property indicates whether <A>ratfun</A> is the zero element of the
## field of rational functions.
## </Description>
## </ManSection>
##
DeclareSynonymAttr("IsZeroRationalFunction",IsZero and IsPolynomialFunction);
InstallTrueMethod( IsConstantRationalFunction,IsZeroRationalFunction );
#############################################################################
##
#R IsRationalFunctionDefaultRep(<obj>)
##
## <#GAPDoc Label="IsRationalFunctionDefaultRep">
## <ManSection>
## <Filt Name="IsRationalFunctionDefaultRep" Arg='obj' Type='Representation'/>
##
## <Description>
## is the default representation of rational functions. A rational function
## in this representation is defined by the attributes
## <Ref Attr="ExtRepNumeratorRatFun"/> and
## <Ref Attr="ExtRepDenominatorRatFun"/>,
## the values of which are external representations of polynomials.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareRepresentation("IsRationalFunctionDefaultRep",
IsComponentObjectRep and IsAttributeStoringRep and IsRationalFunction,
["zeroCoefficient","numerator","denominator"] );
#############################################################################
##
#R IsPolynomialDefaultRep(<obj>)
##
## <#GAPDoc Label="IsPolynomialDefaultRep">
## <ManSection>
## <Filt Name="IsPolynomialDefaultRep" Arg='obj' Type='Representation'/>
##
## <Description>
## is the default representation of polynomials. A polynomial
## in this representation is defined by the components
## and <Ref Attr="ExtRepNumeratorRatFun"/> where
## <Ref Attr="ExtRepNumeratorRatFun"/> is the
## external representation of the polynomial.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareRepresentation("IsPolynomialDefaultRep",
IsComponentObjectRep and IsAttributeStoringRep
and IsPolynomialFunction and IsPolynomial,["zeroCoefficient","numerator"]);
#############################################################################
##
#R IsLaurentPolynomialDefaultRep(<obj>)
##
## <#GAPDoc Label="IsLaurentPolynomialDefaultRep">
## <ManSection>
## <Filt Name="IsLaurentPolynomialDefaultRep" Arg='obj' Type='Representation'/>
##
## <Description>
## This representation is used for Laurent polynomials and univariate
## polynomials. It represents a Laurent polynomial via the attributes
## <Ref Attr="CoefficientsOfLaurentPolynomial"/> and
## <Ref Attr="IndeterminateNumberOfLaurentPolynomial"/>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareRepresentation("IsLaurentPolynomialDefaultRep",
IsComponentObjectRep and IsAttributeStoringRep
and IsPolynomialFunction and IsLaurentPolynomial, [] );
#############################################################################
##
#R IsUnivariateRationalFunctionDefaultRep(<obj>)
##
## <ManSection>
## <Filt Name="IsUnivariateRationalFunctionDefaultRep" Arg='obj' Type='Representation'/>
##
## <Description>
## This representation is used for univariate rational functions
## polynomials. It represents a univariate rational function via the attributes
## <Ref Func="CoefficientsOfUnivariateRationalFunction"/> and
## <Ref Func="IndeterminateNumberOfUnivariateRationalFunction"/>.
## </Description>
## </ManSection>
##
DeclareRepresentation("IsUnivariateRationalFunctionDefaultRep",
IsComponentObjectRep and IsAttributeStoringRep
and IsPolynomialFunction and IsUnivariateRationalFunction, [] );
## <#GAPDoc Label="[1]{ratfun}">
## <Index>External representation of polynomials</Index>
## The representation of a polynomials is a list of the form
## <C>[<A>mon</A>,<A>coeff</A>,<A>mon</A>,<A>coeff</A>,...]</C> where <A>mon</A> is a monomial in
## expanded form (that is given as list) and <A>coeff</A> its coefficient. The
## monomials must be sorted according to the total degree/lexicographic
## order (This is the same as given by the <Q>grlex</Q> monomial ordering,
## see <Ref Func="MonomialGrlexOrdering"/>). We call
## this the <E>external representation</E> of a polynomial. (The
## reason for ordering is that addition of polynomials becomes linear in
## the number of monomials instead of quadratic; the reason for the
## particular ordering chose is that it is compatible with multiplication
## and thus gives acceptable performance for quotient calculations.)
## <#/GAPDoc>
##
## <#GAPDoc Label="[3]{ratfun}">
## The operations <Ref Oper="LaurentPolynomialByCoefficients"/>,
## <Ref Func="PolynomialByExtRep"/> and
## <Ref Func="RationalFunctionByExtRep"/> are used to
## construct objects in the three basic representations for rational
## functions.
## <#/GAPDoc>
#############################################################################
##
#A ExtRepNumeratorRatFun( <ratfun> )
##
## <#GAPDoc Label="ExtRepNumeratorRatFun">
## <ManSection>
## <Attr Name="ExtRepNumeratorRatFun" Arg='ratfun'/>
##
## <Description>
## returns the external representation of the numerator polynomial of the
## rational function <A>ratfun</A>. Numerator and denominator are not guaranteed
## to be cancelled against each other.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute("ExtRepNumeratorRatFun",IsPolynomialFunction);
#############################################################################
##
#A ExtRepDenominatorRatFun( <ratfun> )
##
## <#GAPDoc Label="ExtRepDenominatorRatFun">
## <ManSection>
## <Attr Name="ExtRepDenominatorRatFun" Arg='ratfun'/>
##
## <Description>
## returns the external representation of the denominator polynomial of the
## rational function <A>ratfun</A>. Numerator and denominator are not guaranteed
## to be cancelled against each other.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute("ExtRepDenominatorRatFun",IsRationalFunction);
#############################################################################
##
#O ZeroCoefficientRatFun( <ratfun> )
##
## <#GAPDoc Label="ZeroCoefficientRatFun">
## <ManSection>
## <Oper Name="ZeroCoefficientRatFun" Arg='ratfun'/>
##
## <Description>
## returns the zero of the coefficient ring. This might be needed to
## represent the zero polynomial for which the external representation of
## the numerator is the empty list.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation("ZeroCoefficientRatFun",[IsPolynomialFunction]);
#############################################################################
##
#A ExtRepPolynomialRatFun( <polynomial> )
##
## <#GAPDoc Label="ExtRepPolynomialRatFun">
## <ManSection>
## <Attr Name="ExtRepPolynomialRatFun" Arg='polynomial'/>
##
## <Description>
## returns the external representation of a polynomial. The difference to
## <Ref Attr="ExtRepNumeratorRatFun"/> is that rational functions might know
## to be a polynomial but can still have a non-vanishing denominator.
## In this case
## <Ref Attr="ExtRepPolynomialRatFun"/> has to call a quotient routine.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute("ExtRepPolynomialRatFun",IsPolynomialFunction and IsPolynomial);
#############################################################################
##
#A CoefficientsOfLaurentPolynomial( <laurent> )
##
## <#GAPDoc Label="CoefficientsOfLaurentPolynomial">
## <ManSection>
## <Attr Name="CoefficientsOfLaurentPolynomial" Arg='laurent'/>
##
## <Description>
## For a Laurent polynomial <A>laurent</A>, this function returns a pair
## <C>[<A>cof</A>, <A>val</A>]</C>,
## consisting of the coefficient list (in ascending order) <A>cof</A> and the
## valuation <A>val</A> of <A>laurent</A>.
## <Example><![CDATA[
## gap> p:=LaurentPolynomialByCoefficients(FamilyObj(1),
## > [1,2,3,4,5],-2);
## 5*x^2+4*x+3+2*x^-1+x^-2
## gap> NumeratorOfRationalFunction(p);DenominatorOfRationalFunction(p);
## 5*x^4+4*x^3+3*x^2+2*x+1
## x^2
## gap> CoefficientsOfLaurentPolynomial(p*p);
## [ [ 1, 4, 10, 20, 35, 44, 46, 40, 25 ], -4 ]
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "CoefficientsOfLaurentPolynomial",
IsLaurentPolynomial );
DeclareSynonym( "CoefficientsOfUnivariateLaurentPolynomial",
CoefficientsOfLaurentPolynomial);
#############################################################################
##
#A IndeterminateNumberOfUnivariateRationalFunction( <rfun> )
##
## <#GAPDoc Label="IndeterminateNumberOfUnivariateRationalFunction">
## <ManSection>
## <Attr Name="IndeterminateNumberOfUnivariateRationalFunction" Arg='rfun'/>
##
## <Description>
## returns the number of the indeterminate in which the univariate rational
## function <A>rfun</A> is expressed. (This also provides a way to obtain the
## number of a given indeterminate.)
## <P/>
## A constant rational function might not possess an indeterminate number. In
## this case <Ref Attr="IndeterminateNumberOfUnivariateRationalFunction"/>
## will default to a value of 1.
## Therefore two univariate polynomials may be considered to be in the same
## univariate polynomial ring if their indeterminates have the same number
## or one if of them is constant. (see also <Ref Func="CIUnivPols"/>
## and <Ref Filt="IsLaurentPolynomialDefaultRep"/>).
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "IndeterminateNumberOfUnivariateRationalFunction",
IsUnivariateRationalFunction );
## <#GAPDoc Label="[2]{ratfun}">
## Algorithms should use only the attributes
## <Ref Attr="ExtRepNumeratorRatFun"/>,
## <Ref Attr="ExtRepDenominatorRatFun"/>,
## <Ref Attr="ExtRepPolynomialRatFun"/>,
## <Ref Attr="CoefficientsOfLaurentPolynomial"/> and
## –if the univariate function is not constant–
## <Ref Attr="IndeterminateNumberOfUnivariateRationalFunction"/> as the
## low-level interface to work with a polynomial.
## They should not refer to the actual representation used.
## <#/GAPDoc>
#############################################################################
##
#O LaurentPolynomialByCoefficients( <fam>, <cofs>, <val> [,<ind>] )
##
## <#GAPDoc Label="LaurentPolynomialByCoefficients">
## <ManSection>
## <Oper Name="LaurentPolynomialByCoefficients" Arg='fam, cofs, val [,ind]'/>
##
## <Description>
## constructs a Laurent polynomial over the coefficients
## family <A>fam</A> and in the indeterminate <A>ind</A> (defaulting to 1)
## with the coefficients given by <A>cofs</A> and valuation <A>val</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "LaurentPolynomialByCoefficients",
[ IsFamily, IsList, IsInt, IsInt ] );
DeclareSynonym( "UnivariateLaurentPolynomialByCoefficients",
LaurentPolynomialByCoefficients);
#############################################################################
##
#F LaurentPolynomialByExtRep( <fam>, <cofs>,<val> ,<ind> )
#F LaurentPolynomialByExtRepNC( <fam>, <cofs>,<val> ,<ind> )
##
## <#GAPDoc Label="LaurentPolynomialByExtRep">
## <ManSection>
## <Func Name="LaurentPolynomialByExtRep" Arg='fam, cofs,val ,ind'/>
## <Func Name="LaurentPolynomialByExtRepNC" Arg='fam, cofs,val ,ind'/>
##
## <Description>
## creates a Laurent polynomial in the family <A>fam</A> with [<A>cofs</A>,<A>val</A>] as
## value of <Ref Attr="CoefficientsOfLaurentPolynomial"/>. No coefficient shifting is
## performed. This is the lowest level function to create a Laurent
## polynomial but will rely on the coefficients being shifted properly and
## will not perform any tests. Unless this is guaranteed for the
## parameters,
## <Ref Oper="LaurentPolynomialByCoefficients"/> should be used.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction( "LaurentPolynomialByExtRepNC");
DeclareSynonym("LaurentPolynomialByExtRep",LaurentPolynomialByExtRepNC);
#############################################################################
##
#F PolynomialByExtRep( <rfam>, <extrep> )
#F PolynomialByExtRepNC( <rfam>, <extrep> )
##
## <#GAPDoc Label="PolynomialByExtRep">
## <ManSection>
## <Func Name="PolynomialByExtRep" Arg='rfam, extrep'/>
## <Func Name="PolynomialByExtRepNC" Arg='rfam, extrep'/>
##
## <Description>
## constructs a polynomial
## (in the representation <Ref Filt="IsPolynomialDefaultRep"/>)
## in the rational function family <A>rfam</A>, the polynomial itself is given
## by the external representation <A>extrep</A>.
## <P/>
## The variant <Ref Func="PolynomialByExtRepNC"/> does not perform any test
## of the arguments and thus potentially can create invalid objects. It only
## should be used if speed is required and the arguments are known to be
## in correct form.
## <Example><![CDATA[
## gap> fam:=RationalFunctionsFamily(FamilyObj(1));;
## gap> p:=PolynomialByExtRep(fam,[[1,2],1,[2,1,15,7],3]);
## 3*y*x_15^7+x^2
## gap> q:=p/(p+1);
## (3*y*x_15^7+x^2)/(3*y*x_15^7+x^2+1)
## gap> ExtRepNumeratorRatFun(q);
## [ [ 1, 2 ], 1, [ 2, 1, 15, 7 ], 3 ]
## gap> ExtRepDenominatorRatFun(q);
## [ [ ], 1, [ 1, 2 ], 1, [ 2, 1, 15, 7 ], 3 ]
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction( "PolynomialByExtRep" );
DeclareGlobalFunction( "PolynomialByExtRepNC" );
#############################################################################
##
#F RationalFunctionByExtRep( <rfam>, <num>, <den> )
#F RationalFunctionByExtRepNC( <rfam>, <num>, <den> )
##
## <#GAPDoc Label="RationalFunctionByExtRep">
## <ManSection>
## <Func Name="RationalFunctionByExtRep" Arg='rfam, num, den'/>
## <Func Name="RationalFunctionByExtRepNC" Arg='rfam, num, den'/>
##
## <Description>
## constructs a rational function (in the representation
## <Ref Filt="IsRationalFunctionDefaultRep"/>) in the rational function
## family <A>rfam</A>,
## the rational function itself is given by the external representations
## <A>num</A> and <A>den</A> for numerator and denominator.
## No cancellation takes place.
## <P/>
## The variant <Ref Func="RationalFunctionByExtRepNC"/> does not perform any
## test of the arguments and thus potentially can create illegal objects.
## It only should be used if speed is required and the arguments are known
## to be in correct form.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction( "RationalFunctionByExtRep" );
DeclareGlobalFunction( "RationalFunctionByExtRepNC" );
#############################################################################
##
#F UnivariateRationalFunctionByExtRep(<fam>,<ncof>,<dcof>,<val> ,<ind> )
#F UnivariateRationalFunctionByExtRepNC(<fam>,<ncof>,<dcof>,<val> ,<ind> )
##
## <ManSection>
## <Func Name="UnivariateRationalFunctionByExtRep"
## Arg='fam, ncof, dcof, val, ind'/>
## <Func Name="UnivariateRationalFunctionByExtRepNC"
## Arg='fam, ncof, dcof, val, ind'/>
##
## <Description>
## creates a univariate rational function in the family <A>fam</A> with
## [<A>ncof</A>,<A>dcof</A>,<A>val</A>] as
## value of <Ref Func="CoefficientsOfUnivariateRationalFunction"/>.
## No coefficient shifting is performed.
## This is the lowest level function to create a
## univariate rational function but will rely on the coefficients being
## shifted properly. Unless this is
## guaranteed for the parameters,
## <Ref Func="UnivariateLaurentPolynomialByCoefficients"/> should be used.
## No cancellation is performed.
## <P/>
## The variant <Ref Func="UnivariateRationalFunctionByExtRepNC"/> does not
## perform any test of
## the arguments and thus potentially can create invalid objects. It only
## should be used if speed is required and the arguments are known to be
## in correct form.
## </Description>
## </ManSection>
##
DeclareGlobalFunction( "UnivariateRationalFunctionByExtRepNC");
DeclareSynonym("UnivariateRationalFunctionByExtRep",
UnivariateRationalFunctionByExtRepNC);
#############################################################################
##
#F RationalFunctionByExtRepWithCancellation( <rfam>, <num>, <den> )
##
## <#GAPDoc Label="RationalFunctionByExtRepWithCancellation">
## <ManSection>
## <Func Name="RationalFunctionByExtRepWithCancellation" Arg='rfam, num, den'/>
##
## <Description>
## constructs a rational function as <Ref Func="RationalFunctionByExtRep"/>
## does but tries to cancel out common factors of numerator and denominator,
## calling <Ref Func="TryGcdCancelExtRepPolynomials"/>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction( "RationalFunctionByExtRepWithCancellation" );
#############################################################################
##
#A IndeterminateOfUnivariateRationalFunction( <rfun> )
##
## <#GAPDoc Label="IndeterminateOfUnivariateRationalFunction">
## <ManSection>
## <Attr Name="IndeterminateOfUnivariateRationalFunction" Arg='rfun'/>
##
## <Description>
## returns the indeterminate in which the univariate rational
## function <A>rfun</A> is expressed. (cf.
## <Ref Attr="IndeterminateNumberOfUnivariateRationalFunction"/>.)
## <Example><![CDATA[
## gap> IndeterminateNumberOfUnivariateRationalFunction(z);
## 3
## gap> IndeterminateOfUnivariateRationalFunction(z^5+z);
## X
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "IndeterminateOfUnivariateRationalFunction",
IsUnivariateRationalFunction );
DeclareSynonym("IndeterminateOfLaurentPolynomial",
IndeterminateOfUnivariateRationalFunction);
#############################################################################
##
#F IndeterminateNumberOfLaurentPolynomial(<pol>)
##
## <#GAPDoc Label="IndeterminateNumberOfLaurentPolynomial">
## <ManSection>
## <Attr Name="IndeterminateNumberOfLaurentPolynomial" Arg='pol'/>
##
## <Description>
## Is a synonym for
## <Ref Attr="IndeterminateNumberOfUnivariateRationalFunction"/>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareSynonymAttr("IndeterminateNumberOfLaurentPolynomial",
IndeterminateNumberOfUnivariateRationalFunction);
DeclareSynonymAttr("IndeterminateNumberOfUnivariateLaurentPolynomial",
IndeterminateNumberOfUnivariateRationalFunction);
#############################################################################
##
#O IndeterminateName(<fam>,<nr>)
#O HasIndeterminateName(<fam>,<nr>)
#O SetIndeterminateName(<fam>,<nr>,<name>)
##
## <#GAPDoc Label="IndeterminateName">
## <ManSection>
## <Oper Name="IndeterminateName" Arg='fam,nr'/>
## <Oper Name="HasIndeterminateName" Arg='fam,nr'/>
## <Oper Name="SetIndeterminateName" Arg='fam,nr,name'/>
##
## <Description>
## <Ref Oper="SetIndeterminateName"/> assigns the name <A>name</A> to
## indeterminate <A>nr</A> in the rational functions family <A>fam</A>.
## It issues an error if the indeterminate was already named.
## <P/>
## <Ref Oper="IndeterminateName"/> returns the name of the <A>nr</A>-th
## indeterminate (and returns <K>fail</K> if no name has been assigned).
## <P/>
## <Ref Oper="HasIndeterminateName"/> tests whether indeterminate <A>nr</A>
## has already been assigned a name.
## <P/>
## <Example><![CDATA[
## gap> IndeterminateName(FamilyObj(x),2);
## "y"
## gap> HasIndeterminateName(FamilyObj(x),4);
## false
## gap> SetIndeterminateName(FamilyObj(x),10,"bla");
## gap> Indeterminate(GF(3),10);
## bla
## ]]></Example>
## <P/>
## As a convenience there is a special method installed for <C>SetName</C>
## that will assign a name to an indeterminate.
## <P/>
## <Example><![CDATA[
## gap> a:=Indeterminate(GF(3),5);
## x_5
## gap> SetName(a,"ah");
## gap> a^5+a;
## ah^5+ah
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "IndeterminateName",
[IsPolynomialFunctionsFamily,IsPosInt]);
DeclareOperation( "HasIndeterminateName",
[IsPolynomialFunctionsFamily,IsPosInt]);
DeclareOperation( "SetIndeterminateName",
[IsPolynomialFunctionsFamily,IsPosInt,IsString]);
#############################################################################
##
#A CoefficientsOfUnivariatePolynomial( <pol> )
##
## <#GAPDoc Label="CoefficientsOfUnivariatePolynomial">
## <ManSection>
## <Attr Name="CoefficientsOfUnivariatePolynomial" Arg='pol'/>
##
## <Description>
## <Ref Attr="CoefficientsOfUnivariatePolynomial"/> returns the coefficient
## list of the polynomial <A>pol</A>, sorted in ascending order.
## (It returns the empty list if <A>pol</A> is 0.)
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute("CoefficientsOfUnivariatePolynomial",IsUnivariatePolynomial);
#############################################################################
##
#A DegreeOfLaurentPolynomial( <pol> )
##
## <#GAPDoc Label="DegreeOfLaurentPolynomial">
## <ManSection>
## <Attr Name="DegreeOfLaurentPolynomial" Arg='pol'/>
##
## <Description>
## The degree of a univariate (Laurent) polynomial <A>pol</A> is the largest
## exponent <M>n</M> of a monomial <M>x^n</M> of <A>pol</A>. The degree of
## a zero polynomial is defined to be <C>-infinity</C>.
## <Example><![CDATA[
## gap> p:=UnivariatePolynomial(Rationals,[1,2,3,4],1);
## 4*x^3+3*x^2+2*x+1
## gap> UnivariatePolynomialByCoefficients(FamilyObj(1),[9,2,3,4],73);
## 4*x_73^3+3*x_73^2+2*x_73+9
## gap> CoefficientsOfUnivariatePolynomial(p);
## [ 1, 2, 3, 4 ]
## gap> DegreeOfLaurentPolynomial(p);
## 3
## gap> DegreeOfLaurentPolynomial(Zero(p));
## -infinity
## gap> IndeterminateNumberOfLaurentPolynomial(p);
## 1
## gap> IndeterminateOfLaurentPolynomial(p);
## x
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "DegreeOfLaurentPolynomial",
IsLaurentPolynomial );
DeclareSynonym( "DegreeOfUnivariateLaurentPolynomial",
DegreeOfLaurentPolynomial);
BindGlobal("DEGREE_ZERO_LAURPOL",Ninfinity);
#############################################################################
##
#O UnivariatePolynomialByCoefficients( <fam>, <cofs>, <ind> )
##
## <#GAPDoc Label="UnivariatePolynomialByCoefficients">
## <ManSection>
## <Oper Name="UnivariatePolynomialByCoefficients" Arg='fam, cofs, ind'/>
##
## <Description>
## constructs an univariate polynomial over the coefficients family
## <A>fam</A> and in the indeterminate <A>ind</A> with the coefficients given by
## <A>cofs</A>. This function should be used in algorithms to create
## polynomials as it avoids overhead associated with
## <Ref Oper="UnivariatePolynomial"/>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "UnivariatePolynomialByCoefficients",
[ IsFamily, IsList, IsInt ] );
#############################################################################
##
#O UnivariatePolynomial( <ring>, <cofs>[, <ind>] )
##
## <#GAPDoc Label="UnivariatePolynomial">
## <ManSection>
## <Oper Name="UnivariatePolynomial" Arg='ring, cofs[, ind]'/>
##
## <Description>
## constructs an univariate polynomial over the ring <A>ring</A> in the
## indeterminate <A>ind</A> with the coefficients given by <A>cofs</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "UnivariatePolynomial",
[ IsRing, IsRingElementCollection, IsPosInt ] );
#############################################################################
##
#A CoefficientsOfUnivariateRationalFunction( <rfun> )
##
## <#GAPDoc Label="CoefficientsOfUnivariateRationalFunction">
## <ManSection>
## <Attr Name="CoefficientsOfUnivariateRationalFunction" Arg='rfun'/>
##
## <Description>
## if <A>rfun</A> is a univariate rational function, this attribute
## returns a list <C>[ <A>ncof</A>, <A>dcof</A>, <A>val</A> ]</C>
## where <A>ncof</A> and <A>dcof</A> are coefficient lists of univariate
## polynomials <A>n</A> and <A>d</A> and a valuation <A>val</A> such that
## <M><A>rfun</A> = x^{<A>val</A>} \cdot <A>n</A> / <A>d</A></M>
## where <M>x</M> is the variable with the number given by
## <Ref Attr="IndeterminateNumberOfUnivariateRationalFunction"/>.
## Numerator and denominator are guaranteed to be cancelled.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "CoefficientsOfUnivariateRationalFunction",
IsUnivariateRationalFunction );
#############################################################################
##
#O UnivariateRationalFunctionByCoefficients(<fam>,<ncof>,<dcof>,<val>[,<ind>])
##
## <#GAPDoc Label="UnivariateRationalFunctionByCoefficients">
## <ManSection>
## <Oper Name="UnivariateRationalFunctionByCoefficients"
## Arg='fam, ncof, dcof, val[, ind]'/>
##
## <Description>
## constructs a univariate rational function over the coefficients
## family <A>fam</A> and in the indeterminate <A>ind</A> (defaulting to 1) with
## numerator and denominator coefficients given by <A>ncof</A> and <A>dcof</A> and
## valuation <A>val</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "UnivariateRationalFunctionByCoefficients",
[ IsFamily, IsList, IsList, IsInt, IsInt ] );
#############################################################################
##
#O Value(<ratfun>,<indets>,<vals>[,<one>])
#O Value(<upol>,<value>[,<one>])
##
## <#GAPDoc Label="Value">
## <ManSection>
## <Heading>Value</Heading>
## <Oper Name="Value" Arg='ratfun, indets, vals[, one]'
## Label="for rat. function, a list of indeterminates, a value (and a one)"/>
## <Oper Name="Value" Arg='upol, value[, one]'
## Label="for a univariate rat. function, a value (and a one)"/>
##
## <Description>
## The first variant takes a rational function <A>ratfun</A> and specializes
## the indeterminates given in <A>indets</A> to the values given in
## <A>vals</A>,
## replacing the <M>i</M>-th entry in <A>indets</A> by the <M>i</M>-th entry
## in <A>vals</A>.
## If this specialization results in a constant polynomial,
## an element of the coefficient ring is returned.
## If the specialization would specialize the denominator of <A>ratfun</A>
## to zero, an error is raised.
## <P/>
## A variation is the evaluation at elements of another ring <M>R</M>,
## for which a multiplication with elements of the coefficient ring of
## <A>ratfun</A> are defined.
## In this situation the identity element of <M>R</M> may be given by a
## further argument <A>one</A> which will be used for <M>x^0</M> for any
## specialized indeterminate <M>x</M>.
## <P/>
## The second version takes an univariate rational function and specializes
## the value of its indeterminate to <A>val</A>.
## Again, an optional argument <A>one</A> may be given.
## <C>Value( <A>upol</A>, <A>val</A> )</C> can also be expressed as <C>upol(
## <A>val</A> )</C>.
## <P/>
## <Example><![CDATA[
## gap> Value(x*y+y+x^7,[x,y],[5,7]);
## 78167
## ]]></Example>
## <P/>
## Note that the default values for <A>one</A> can lead to different results
## than one would expect:
## For example for a matrix <M>M</M>, the values <M>M+M^0</M> and <M>M+1</M>
## are <E>different</E>.
## As <Ref Oper="Value" Label="for rat. function, a list of indeterminates, a value (and a one)"/>
## defaults to the one of the coefficient ring,
## when evaluating matrices in polynomials always the correct <A>one</A>
## should be given!
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation("Value",[IsPolynomialFunction,IsList,IsList]);
#############################################################################
##
#F OnIndeterminates(<poly>,<perm>)
##
## <#GAPDoc Label="OnIndeterminates">
## <ManSection>
## <Func Name="OnIndeterminates" Arg='poly, perm'
## Label="as a permutation action"/>
##
## <Description>
## A permutation <A>perm</A> acts on the multivariate polynomial <A>poly</A>
## by permuting the indeterminates as it permutes points.
## <Example><![CDATA[
## gap> x:=Indeterminate(Rationals,1);; y:=Indeterminate(Rationals,2);;
## gap> OnIndeterminates(x^7*y+x*y^4,(1,17)(2,28));
## x_17^7*x_28+x_17*x_28^4
## gap> Stabilizer(Group((1,2,3,4),(1,2)),x*y,OnIndeterminates);
## Group([ (1,2), (3,4) ])
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("OnIndeterminates");
#############################################################################
##
#F ConstituentsPolynomial(<pol>)
##
## <ManSection>
## <Func Name="ConstituentsPolynomial" Arg='pol'/>
##
## <Description>
## Given a polynomial <A>pol</A> this function returns a record with
## components
## <List>
## <Mark><C>variables</C>:</Mark>
## <Item>
## A list of the variables occurring in <A>pol</A>,
## </Item>
## <Mark><C>monomials</C>:</Mark>
## <Item>
## A list of the monomials in <A>pol</A>, and
## </Item>
## <Mark><C>coefficients</C>:</Mark>
## <Item>
## A (corresponding) list of coefficients.
## </Item>
## </List>
## </Description>
## </ManSection>
##
DeclareGlobalFunction("ConstituentsPolynomial");
## <#GAPDoc Label="[4]{ratfun}">
## <Index>Expanded form of monomials</Index>
## A monomial is a product of powers of indeterminates. A monomial is
## stored as a list (we call this the <E>expanded form</E> of the monomial)
## of the form <C>[<A>inum</A>,<A>exp</A>,<A>inum</A>,<A>exp</A>,...]</C> where each <A>inum</A>
## is the number of an indeterminate and <A>exp</A> the corresponding exponent.
## The list must be sorted according to the numbers of the indeterminates.
## Thus for example, if <M>x</M>, <M>y</M> and <M>z</M> are the first three indeterminates,
## the expanded form of the monomial <M>x^5 z^8 = z^8 x^5</M> is
## <C>[ 1, 5, 3, 8 ]</C>.
## <#/GAPDoc>
#############################################################################
##
#F MonomialExtGrlexLess(<a>,<b>)
##
## <#GAPDoc Label="MonomialExtGrlexLess">
## <ManSection>
## <Func Name="MonomialExtGrlexLess" Arg='a,b'/>
##
## <Description>
## implements comparison of monomial in their external representation by a
## <Q>grlex</Q> order with <M>x_1>x_2</M>
## (This is exactly the same as the ordering by
## <Ref Func="MonomialGrlexOrdering"/>,
## see <Ref Sect="Monomial Orderings"/>).
## The function takes two
## monomials <A>a</A> and <A>b</A> in expanded form and returns whether the first is
## smaller than the second. (This ordering is also used by &GAP;
## internally for representing polynomials as a linear combination of
## monomials.)
## <P/>
## See section <Ref Sect="The Defining Attributes of Rational Functions"/> for details
## on the expanded form of monomials.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("MonomialExtGrlexLess");
#############################################################################
##
#F LeadingMonomial(<pol>) . . . . . . . . leading monomial of a polynomial
##
## <#GAPDoc Label="LeadingMonomial">
## <ManSection>
## <Oper Name="LeadingMonomial" Arg='pol'/>
##
## <Description>
## returns the leading monomial (with respect to the ordering given by
## <Ref Func="MonomialExtGrlexLess"/>) of the polynomial <A>pol</A> as a list
## containing indeterminate numbers and exponents.
## <Example><![CDATA[
## gap> LeadingCoefficient(f,1);
## 1
## gap> LeadingCoefficient(f,2);
## 9
## gap> LeadingMonomial(f);
## [ 2, 7 ]
## gap> LeadingCoefficient(f);
## 9
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "LeadingMonomial", [ IsPolynomialFunction ] );
#############################################################################
##
#O LeadingCoefficient( <pol> )
##
## <#GAPDoc Label="LeadingCoefficient">
## <ManSection>
## <Oper Name="LeadingCoefficient" Arg='pol'/>
##
## <Description>
## returns the leading coefficient (that is the coefficient of the leading
## monomial, see <Ref Oper="LeadingMonomial"/>) of the polynomial <A>pol</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation("LeadingCoefficient", [IsPolynomialFunction]);
#############################################################################
##
#F LeadingMonomialPosExtRep(<fam>,<ext>,<order>)
##
## <ManSection>
## <Func Name="LeadingMonomialPosExtRep" Arg='fam,ext,order'/>
##
## <Description>
## This function takes an external representation <A>ext</A> of a polynomial in
## family <A>fam</A> and returns the position of the leading monomial in <A>ext</A>
## with respect to the monomial order implemented by the function <A>order</A>.
## <P/>
## See section <Ref Sect="The Defining Attributes of Rational Functions"/> for details
## on the external representation.
## </Description>
## </ManSection>
##
DeclareGlobalFunction("LeadingMonomialPosExtRep");
## The following set of functions consider one indeterminate of a multivariate
## polynomial specially
#############################################################################
##
#O PolynomialCoefficientsOfPolynomial( <pol>, <ind> )
##
## <#GAPDoc Label="PolynomialCoefficientsOfPolynomial">
## <ManSection>
## <Oper Name="PolynomialCoefficientsOfPolynomial" Arg='pol, ind'/>
##
## <Description>
## <Ref Oper="PolynomialCoefficientsOfPolynomial"/> returns the
## coefficient list (whose entries are polynomials not involving the
## indeterminate <A>ind</A>) describing the polynomial <A>pol</A> viewed as
## a polynomial in <A>ind</A>.
## Instead of the indeterminate,
## <A>ind</A> can also be an indeterminate number.
## <Example><![CDATA[
## gap> PolynomialCoefficientsOfPolynomial(f,2);
## [ x^5+2, 3*x+3, 0, 0, 0, 4*x, 0, 9 ]
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "PolynomialCoefficientsOfPolynomial",
[ IsPolynomial,IsPosInt]);
#############################################################################
##
#O DegreeIndeterminate( <pol>,<ind> )
##
## <#GAPDoc Label="DegreeIndeterminate">
## <ManSection>
## <Oper Name="DegreeIndeterminate" Arg='pol, ind'/>
##
## <Description>
## returns the degree of the polynomial <A>pol</A> in the indeterminate
## (or indeterminate number) <A>ind</A>.
## <Example><![CDATA[
## gap> f:=x^5+3*x*y+9*y^7+4*y^5*x+3*y+2;
## 9*y^7+4*x*y^5+x^5+3*x*y+3*y+2
## gap> DegreeIndeterminate(f,1);
## 5
## gap> DegreeIndeterminate(f,y);
## 7
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation("DegreeIndeterminate",[IsPolynomial,IsPosInt]);
#############################################################################
##
#A Derivative( <ratfun>[, <ind>] )
##
## <#GAPDoc Label="Derivative">
## <ManSection>
## <Attr Name="Derivative" Arg='ratfun[, ind]'/>
##
## <Description>
## If <A>ratfun</A> is a univariate rational function then
## <Ref Attr="Derivative"/> returns the <E>derivative</E> of <A>ufun</A> by
## its indeterminate.
## For a rational function <A>ratfun</A>,
## the derivative by the indeterminate <A>ind</A> is returned,
## regarding <A>ratfun</A> as univariate in <A>ind</A>.
## Instead of the desired indeterminate, also the number of this
## indeterminate can be given as <A>ind</A>.
## <Example><![CDATA[
## gap> Derivative(f,2);
## 63*y^6+20*x*y^4+3*x+3
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute("Derivative",IsUnivariateRationalFunction);
DeclareOperation("Derivative",[IsPolynomialFunction,IsPosInt]);
#############################################################################
##
#A TaylorSeriesRationalFunction( <ratfun>, <at>, <deg> )
##
## <#GAPDoc Label="TaylorSeriesRationalFunction">
## <ManSection>
## <Attr Name="TaylorSeriesRationalFunction" Arg='ratfun, at, deg]'/>
##
## <Description>
## Computes the taylor series up to degree <A>deg</A> of <A>ratfun</A> at
## <A>at</A>.
## <Example><![CDATA[
## gap> TaylorSeriesRationalFunction((x^5+3*x+7)/(x^5+x+1),0,11);
## -50*x^11+36*x^10-26*x^9+22*x^8-18*x^7+14*x^6-10*x^5+4*x^4-4*x^3+4*x^2-4*x+7
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("TaylorSeriesRationalFunction");
#############################################################################
##
#O Resultant( <pol1>, <pol2>, <ind> )
##
## <#GAPDoc Label="Resultant">
## <ManSection>
## <Oper Name="Resultant" Arg='pol1, pol2, ind'/>
##
## <Description>
## computes the resultant of the polynomials <A>pol1</A> and <A>pol2</A>
## with respect to the indeterminate <A>ind</A>,
## or indeterminate number <A>ind</A>.
## The resultant considers <A>pol1</A> and <A>pol2</A> as univariate in
## <A>ind</A> and returns an element of the corresponding base ring
## (which might be a polynomial ring).
## <Example><![CDATA[
## gap> Resultant(x^4+y,y^4+x,1);
## y^16+y
## gap> Resultant(x^4+y,y^4+x,2);
## x^16+x
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "Resultant",[ IsPolynomial, IsPolynomial, IsPosInt]);
#############################################################################
##
#O Discriminant( <pol>[, <ind>] )
##
## <#GAPDoc Label="Discriminant">
## <ManSection>
## <Oper Name="Discriminant" Arg='pol[, ind]'/>
##
## <Description>
## If <A>pol</A> is a univariate polynomial then
## <Ref Oper="Discriminant"/> returns the <E>discriminant</E> of <A>pol</A>
## by its indeterminate.
## The two-argument form returns the discriminant of a polynomial <A>pol</A>
## by the indeterminate number <A>ind</A>, regarding <A>pol</A> as univariate
## in this indeterminate. Instead of the indeterminate number, the
## indeterminate itself can also be given as <A>ind</A>.
## <Example><![CDATA[
## gap> Discriminant(f,1);
## 20503125*y^28+262144*y^25+27337500*y^22+19208040*y^21+1474560*y^17+136\
## 68750*y^16+18225000*y^15+6075000*y^14+1105920*y^13+3037500*y^10+648972\
## 0*y^9+4050000*y^8+900000*y^7+62208*y^5+253125*y^4+675000*y^3+675000*y^\
## 2+300000*y+50000
## gap> Discriminant(f,1) = Discriminant(f,x);
## true
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareAttribute( "Discriminant", IsPolynomial );
DeclareOperation( "Discriminant", [ IsPolynomial, IsPosInt ] );
## Technical functions for rational functions
#############################################################################
##
#F CIUnivPols( <upol1>, <upol2> )
##
## <#GAPDoc Label="CIUnivPols">
## <ManSection>
## <Func Name="CIUnivPols" Arg='upol1, upol2'/>
##
## <Description>
## This function (whose name stands for
## <Q>common indeterminate of univariate polynomials</Q>) takes two
## univariate polynomials as arguments.
## If both polynomials are given in the same indeterminate number
## <A>indnum</A> (in this case they are <Q>compatible</Q> as
## univariate polynomials) it returns <A>indnum</A>.
## In all other cases it returns <K>fail</K>.
## <Ref Func="CIUnivPols"/> also accepts if either polynomial is constant
## but formally expressed in another indeterminate, in this situation the
## indeterminate of the other polynomial is selected.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("CIUnivPols");
#############################################################################
##
#F TryGcdCancelExtRepPolynomials(<fam>,<a>,<b>);
##
## <#GAPDoc Label="TryGcdCancelExtRepPolynomials">
## <ManSection>
## <Func Name="TryGcdCancelExtRepPolynomials" Arg='fam,a,b'/>
##
## <Description>
## Let <A>a</A> and <A>b</A> be the external representations of two
## polynomials.
## This function tries to cancel common factors between the corresponding
## polynomials and returns a list <M>[ a', b' ]</M> of
## external representations of cancelled polynomials.
## As there is no proper multivariate GCD
## cancellation is not guaranteed to be optimal.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("TryGcdCancelExtRepPolynomials");
#############################################################################
##
#O HeuristicCancelPolynomialsExtRep(<fam>,<ext1>,<ext2>)
##
## <#GAPDoc Label="HeuristicCancelPolynomialsExtRep">
## <ManSection>
## <Oper Name="HeuristicCancelPolynomialsExtRep" Arg='fam,ext1,ext2'/>
##
## <Description>
## is called by <Ref Func="TryGcdCancelExtRepPolynomials"/> to perform the
## actual work.
## It will return either <K>fail</K> or a new list of external
## representations of cancelled polynomials.
## The cancellation performed is not necessarily optimal.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation("HeuristicCancelPolynomialsExtRep",
[IsRationalFunctionsFamily,IsList,IsList]);
#############################################################################
##
#F QuotientPolynomialsExtRep(<fam>,<a>,<b>)
##
## <#GAPDoc Label="QuotientPolynomialsExtRep">
## <ManSection>
## <Func Name="QuotientPolynomialsExtRep" Arg='fam,a,b'/>
##
## <Description>
## Let <A>a</A> and <A>b</A> the external representations of two polynomials
## in the rational functions family <A>fam</A>.
## This function computes the external representation of the quotient of
## both polynomials,
## it returns <K>fail</K> if the polynomial described by <A>b</A> does not
## divide the polynomial described by <A>a</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("QuotientPolynomialsExtRep");
#############################################################################
##
#F QuotRemLaurpols(<left>,<right>,<mode>)
##
## <#GAPDoc Label="QuotRemLaurpols">
## <ManSection>
## <Func Name="QuotRemLaurpols" Arg='left,right,mode'/>
##
## <Description>
## This internal function for euclidean division of polynomials
## takes two polynomials <A>left</A> and <A>right</A>
## and computes their quotient. No test is performed whether the arguments
## indeed are polynomials.
## Depending on the integer variable <A>mode</A>, which may take values in
## a range from 1 to 4, it returns respectively:
## <Enum>
## <Item>
## the quotient (there might be some remainder),
## </Item>
## <Item>
## the remainder,
## </Item>
## <Item>
## a list <C>[<A>q</A>,<A>r</A>]</C> of quotient and remainder,
## </Item>
## <Item>
## the quotient if there is no remainder and <K>fail</K> otherwise.
## </Item>
## </Enum>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("QuotRemLaurpols");
#############################################################################
##
#F GcdCoeffs(<a>,<b>)
##
## <ManSection>
## <Func Name="GcdCoeffs" Arg='a,b'/>
##
## <Description>
## computes the univariate gcd coefficient list from coefficient lists.
## </Description>
## </ManSection>
##
DeclareGlobalFunction("GcdCoeffs");
#############################################################################
##
#F UnivariatenessTestRationalFunction(<f>)
##
## <#GAPDoc Label="UnivariatenessTestRationalFunction">
## <ManSection>
## <Func Name="UnivariatenessTestRationalFunction" Arg='f'/>
##
## <Description>
## takes a rational function <A>f</A> and tests whether it is univariate
## rational function (or even a Laurent polynomial). It returns a list
## <C>[isunivariate, indet, islaurent, cofs]</C>.
## <P/>
## If <A>f</A> is a univariate rational function then <C>isunivariate</C>
## is <K>true</K> and <C>indet</C> is the number of the appropriate
## indeterminate.
## <P/>
## Furthermore, if <A>f</A> is a Laurent polynomial, then <C>islaurent</C>
## is also <K>true</K>. In this case the fourth entry, <C>cofs</C>, is
## the value of the attribute <Ref Attr="CoefficientsOfLaurentPolynomial"/>
## for <A>f</A>.
## <P/>
## If <C>isunivariate</C> is <K>true</K> but <C>islaurent</C> is
## <K>false</K>, then <C>cofs</C> is the value of the attribute
## <Ref Attr="CoefficientsOfUnivariateRationalFunction"/> for <A>f</A>.
## <P/>
## Otherwise, each entry of the returned list is equal to <K>fail</K>.
## As there is no proper multivariate gcd, this may also happen for the
## rational function which may be reduced to univariate (see example).
## <Example><![CDATA[
## gap> UnivariatenessTestRationalFunction( 50-45*x-6*x^2+x^3 );
## [ true, 1, true, [ [ 50, -45, -6, 1 ], 0 ] ]
## gap> UnivariatenessTestRationalFunction( (-6*y^2+y^3) / (y+1) );
## [ true, 2, false, [ [ -6, 1 ], [ 1, 1 ], 2 ] ]
## gap> UnivariatenessTestRationalFunction( (-6*y^2+y^3) / (x+1));
## [ false, fail, false, fail ]
## gap> UnivariatenessTestRationalFunction( ((y+2)*(x+1)) / ((y-1)*(x+1)) );
## [ fail, fail, fail, fail ]
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareGlobalFunction("UnivariatenessTestRationalFunction");
#############################################################################
##
#F SpecializedExtRepPol(<fam>,<ext>,<ind>,<val>)
##
## <ManSection>
## <Func Name="SpecializedExtRepPol" Arg='fam,ext,ind,val'/>
##
## <Description>
## specializes the indeterminate <A>ind</A> in the polynomial ext rep to <A>val</A>
## and returns the resulting polynomial ext rep.
## </Description>
## </ManSection>
##
DeclareGlobalFunction("SpecializedExtRepPol");
#############################################################################
##
#F RandomPol(<ring>,<deg>[,<indnum>])
##
## <ManSection>
## <Func Name="RandomPol" Arg='ring,deg[,indnum]'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareGlobalFunction("RandomPol");
#############################################################################
##
#O ZippedSum( <z1>, <z2>, <czero>, <funcs> )
##
## <#GAPDoc Label="ZippedSum">
## <ManSection>
## <Oper Name="ZippedSum" Arg='z1, z2, czero, funcs'/>
##
## <Description>
## computes the sum of two external representations of polynomials
## <A>z1</A> and <A>z2</A>.
## <A>czero</A> is the appropriate coefficient zero and <A>funcs</A> a list
## [ <A>monomial_less</A>, <A>coefficient_sum</A> ] containing a monomial
## comparison and a coefficient addition function.
## This list can be found in the component <A>fam</A><C>!.zippedSum</C>
## of the rational functions family.
## <P/>
## Note that <A>coefficient_sum</A> must be a proper <Q>summation</Q>
## function, not a function computing differences.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "ZippedSum", [ IsList, IsList, IsObject, IsList ] );
#############################################################################
##
#O ZippedProduct( <z1>, <z2>, <czero>, <funcs> )
##
## <#GAPDoc Label="ZippedProduct">
## <ManSection>
## <Oper Name="ZippedProduct" Arg='z1, z2, czero, funcs'/>
##
## <Description>
## computes the product of two external representations of polynomials
## <A>z1</A> and <A>z2</A>.
## <A>czero</A> is the appropriate coefficient zero and <A>funcs</A> a list
## [ <A>monomial_prod</A>, <A>monomial_less</A>, <A>coefficient_sum</A>,
## <A>coefficient_prod</A>] containing functions to multiply and compare
## monomials, to add and to multiply coefficients.
## This list can be found in the component <C><A>fam</A>!.zippedProduct</C>
## of the rational functions family.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "ZippedProduct", [ IsList, IsList, IsObject, IsList ] );
DeclareGlobalFunction( "ProdCoefRatfun" );
DeclareGlobalFunction( "SumCoefRatfun" );
DeclareGlobalFunction( "SumCoefPolynomial" );
## The following functions are intended to permit the calculations with
## (Laurent) Polynomials over Rings which are not an UFD. In this case it
## is not possible to create the field of rational functions (and thus no
## rational functions family exists.
#############################################################################
##
#C IsLaurentPolynomialsFamilyElement
##
## <ManSection>
## <Filt Name="IsLaurentPolynomialsFamilyElement" Arg='obj' Type='Category'/>
##
## <Description>
## constructs a family containing all Laurent polynomials with coefficients
## in <A>family</A> for a family which has a one and is commutative. The
## external representation looks like the one for <C>RationalsFunctionsFamily</C>
## so if one really wants rational functions where the denominator is a
## non-zero-divisor <C>LaurentPolynomialFunctionsFamily</C> can easily be changed
## to <C>RestrictedRationalsFunctionsFamily</C>.
## </Description>
## </ManSection>
##
DeclareCategory( "IsLaurentPolynomialsFamilyElement", IsRationalFunction );
#############################################################################
##
#C IsUnivariatePolynomialsFamilyElement
##
## <ManSection>
## <Filt Name="IsUnivariatePolynomialsFamilyElement" Arg='obj' Type='Category'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareCategory( "IsUnivariatePolynomialsFamilyElement",
IsRationalFunction );
#############################################################################
##
#C IsLaurentPolynomialsFamily(<obj>)
##
## <ManSection>
## <Filt Name="IsLaurentPolynomialsFamily" Arg='obj' Type='Category'/>
##
## <Description>
## At present Laurent polynomials families only exist if the coefficients
## family is commutative and has a one.
## <P/>
## <!-- 1996/10/14 fceller can this be done with <C>CategoryFamily</C>?-->
## </Description>
## </ManSection>
##
DeclareCategory( "IsLaurentPolynomialsFamily",
IsFamily and HasOne and IsCommutativeFamily );
#############################################################################
##
#C IsUnivariatePolynomialsFamily
##
## <ManSection>
## <Filt Name="IsUnivariatePolynomialsFamily" Arg='obj' Type='Category'/>
##
## <Description>
## At present univariate polynomials families only exist if the coefficients
## family is a skew field.
## <P/>
## <!-- 1996/10/14 fceller can this be done with <C>CategoryFamily</C>?-->
## </Description>
## </ManSection>
##
DeclareCategory( "IsUnivariatePolynomialsFamily", IsFamily );
## `IsRationalFunctionsFamilyElement', an element of a Laurent
## polynomials family has category `IsLaurentPolynomialsFamilyElement', and
## an element of a univariate polynomials family has category
## `IsUnivariatePolynomialsFamilyElement'. They all lie in the super
## category `IsRationalFunction'.
##
## `IsPolynomial', `IsUnivariatePolynomials', `IsLaurentPolynomial', and
## `IsUnivariateLaurentPolynomial' are properties of rational functions.
##
## The basic operations for rational functions are:
##
## `ExtRepOfObj'
## `ObjByExtRep'.
##
## The basic operations for rational functions which are univariate Laurent
## polynomials are:
##
## `UnivariateLaurentPolynomialByCoefficients'
## `CoefficientsOfUnivariateLaurentPolynomial'
## `IndeterminateNumberOfUnivariateLaurentPolynomial'
##
#needed as ``forward''-declaration.
DeclareGlobalFunction("MultivariateFactorsPolynomial");
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