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/usr/share/axiom-20170501/src/algebra/ZDSOLVE.spad is in axiom-source 20170501-3.

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)abbrev package ZDSOLVE ZeroDimensionalSolvePackage
++ Author: Marc Moreno Maza
++ Date Created: 23/01/1999
++ Date Last Updated: 08/02/1999
++ Description: 
++ A package for computing symbolically the complex and real roots of 
++ zero-dimensional algebraic systems over the integer or rational
++ numbers. Complex roots are given by means of univariate representations
++ of irreducible regular chains. Real roots are given by means of tuples
++ of coordinates lying in the \spadtype{RealClosure} of the coefficient ring.
++ This constructor takes three arguments. The first one \spad{R} is the
++ coefficient ring. The second one \spad{ls} is the list of variables 
++ involved in the systems to solve. The third one must be \spad{concat(ls,s)}
++ where \spad{s} is an additional symbol used for the univariate 
++ representations.
++ WARNING. The third argument is not checked.
++ All operations are based on triangular decompositions.
++ The default is to compute these decompositions directly from the input
++ system by using the \spadtype{RegularChain} domain constructor.
++ The lexTriangular algorithm can also be used for computing these 
++ decompositions (see \spadtype{LexTriangularPackage} package constructor).
++ For that purpose, the operations univariateSolve, realSolve and 
++ positiveSolve admit an optional argument.

ZeroDimensionalSolvePackage(R,ls,ls2) : SIG == CODE where
  R : Join(OrderedRing,EuclideanDomain,CharacteristicZero,RealConstant)
  ls: List Symbol
  ls2: List Symbol

  V ==> OrderedVariableList(ls)
  N ==> NonNegativeInteger
  Z ==> Integer
  B ==> Boolean
  P ==> Polynomial R
  LP ==> List P
  LS ==> List Symbol
  Q ==> NewSparseMultivariatePolynomial(R,V)
  U ==> SparseUnivariatePolynomial(R)
  TS ==> RegularChain(R,ls)
  RUR ==> Record(complexRoots: U, coordinates: LP) 
  K ==> Fraction R
  RC ==> RealClosure(K)
  PRC ==> Polynomial RC
  REALSOL ==> List RC
  URC ==> SparseUnivariatePolynomial RC
  V2 ==> OrderedVariableList(ls2)
  Q2 ==> NewSparseMultivariatePolynomial(R,V2)
  E2 ==> IndexedExponents V2
  ST ==> SquareFreeRegularTriangularSet(R,E2,V2,Q2)
  Q2WT ==> Record(val: Q2, tower: ST)
  LQ2WT ==> Record(val: List(Q2), tower: ST)
  WIP ==> Record(reals: List(RC), vars: List(Symbol), pols: List(Q2))
  polsetpack ==> PolynomialSetUtilitiesPackage(R,E2,V2,Q2)
  normpack ==> NormalizationPackage(R,E2,V2,Q2,ST)
  rurpack ==> InternalRationalUnivariateRepresentationPackage(R,E2,V2,Q2,ST)
  quasicomppack ==> SquareFreeQuasiComponentPackage(R,E2,V2,Q2,ST)
  lextripack ==> LexTriangularPackage(R,ls)

  SIG ==> with

    triangSolve : (LP,B,B) -> List RegularChain(R,ls)
      ++ \spad{triangSolve(lp,info?,lextri?)} decomposes the variety
      ++ associated with \axiom{lp} into regular chains.
      ++ Thus a point belongs to this variety iff it is a regular
      ++ zero of a regular set in in the output.
      ++ Note that \axiom{lp} needs to generate a zero-dimensional ideal.
      ++ If \axiom{lp} is not zero-dimensional then the result is only
      ++ a decomposition of its zero-set in the sense of the closure
      ++ (w.r.t. Zarisky topology).
      ++ Moreover, if \spad{info?} is \spad{true} then some information is 
      ++ displayed during the computations.
      ++ See zeroSetSplit from RegularTriangularSetCategory(lp,true,info?).
      ++ If \spad{lextri?} is \spad{true} then the lexTriangular algorithm 
      ++ is called
      ++ from the \spadtype{LexTriangularPackage} constructor
      ++ (see zeroSetSplit from LexTriangularPackage(lp,false)).
      ++ Otherwise, the triangular decomposition is computed directly from 
      ++ the input
      ++ system by using the zeroSetSplit from RegularChain 

    triangSolve : (LP,B) -> List RegularChain(R,ls)
      ++ \spad{triangSolve(lp,info?)} returns the same as 
      ++ \spad{triangSolve(lp,false)}

    triangSolve : LP -> List RegularChain(R,ls)
      ++ \spad{triangSolve(lp)} returns the same as 
      ++ \spad{triangSolve(lp,false,false)}

    univariateSolve : RegularChain(R,ls) -> _
                  List Record(complexRoots: U, coordinates: LP) 
      ++ \spad{univariateSolve(ts)} returns a univariate representation
      ++ of \spad{ts}.
      ++ See rur from RationalUnivariateRepresentationPackage(lp,true).

    univariateSolve : (LP,B,B,B) -> List RUR
      ++ \spad{univariateSolve(lp,info?,check?,lextri?)} returns a univariate 
      ++ representation of the variety associated with \spad{lp}. 
      ++ Moreover, if \spad{info?} is \spad{true} then some information is 
      ++ displayed during the decomposition into regular chains.
      ++ If \spad{check?} is \spad{true} then the result is checked.
      ++ See rur from RationalUnivariateRepresentationPackage(lp,true).
      ++ If \spad{lextri?} is \spad{true} then the lexTriangular 
      ++ algorithm is called
      ++ from the \spadtype{LexTriangularPackage} constructor
      ++ (see zeroSetSplit from LexTriangularPackage(lp,false)).
      ++ Otherwise, the triangular decomposition is computed directly 
      ++ from the input
      ++ system by using the zeroSetSplit from RegularChain 

    univariateSolve : (LP,B,B) -> List RUR
      ++ \spad{univariateSolve(lp,info?,check?)} returns the same as
      ++ \spad{univariateSolve(lp,info?,check?,false)}.

    univariateSolve : (LP,B) -> List RUR
      ++ \spad{univariateSolve(lp,info?)} returns the same as
      ++ \spad{univariateSolve(lp,info?,false,false)}.

    univariateSolve: LP -> List RUR
      ++ \spad{univariateSolve(lp)} returns the same as
      ++ \spad{univariateSolve(lp,false,false,false)}.

    realSolve : RegularChain(R,ls) -> List REALSOL
      ++ \spad{realSolve(ts)} returns the set of the points in the regular
      ++ zero set of \spad{ts} whose coordinates are all real.
      ++ WARNING. For each set of coordinates given by \spad{realSolve(ts)} 
      ++ the ordering of the indeterminates is reversed w.r.t. \spad{ls}.

    realSolve : (LP,B,B,B) -> List REALSOL
      ++ \spad{realSolve(ts,info?,check?,lextri?)} returns the set of the 
      ++ points in the variety associated with \spad{lp} whose coordinates 
      ++ are all real.
      ++ Moreover, if \spad{info?} is \spad{true} then some information is 
      ++ displayed during decomposition into regular chains.
      ++ If \spad{check?} is \spad{true} then the result is checked.
      ++ If \spad{lextri?} is \spad{true} then the lexTriangular algorithm 
      ++ is called
      ++ from the \spadtype{LexTriangularPackage} constructor
      ++ (see zeroSetSplit from LexTriangularPackage(lp,false)).
      ++ Otherwise, the triangular decomposition is computed directly from 
      ++ the input
      ++ system by using the zeroSetSplit from \spadtype{RegularChain}.
      ++ WARNING. For each set of coordinates given by 
      ++ \spad{realSolve(ts,info?,check?,lextri?)}
      ++ the ordering of the indeterminates is reversed w.r.t. \spad{ls}.

    realSolve : (LP,B,B) -> List REALSOL
      ++ \spad{realSolve(ts,info?,check?)} returns the same as 
      ++ \spad{realSolve(ts,info?,check?,false)}.

    realSolve : (LP,B) -> List REALSOL
      ++ \spad{realSolve(ts,info?)} returns the same as 
      ++ \spad{realSolve(ts,info?,false,false)}.

    realSolve : LP -> List REALSOL
      ++ \spad{realSolve(lp)} returns the same as 
      ++ \spad{realSolve(ts,false,false,false)} 

    positiveSolve : RegularChain(R,ls)  -> List REALSOL
      ++ \spad{positiveSolve(ts)} returns the points of the regular
      ++ set of \spad{ts} with (real) strictly positive coordinates.

    positiveSolve : (LP,B,B) -> List REALSOL
      ++ \spad{positiveSolve(lp,info?,lextri?)} returns the set of the points 
      ++ in the variety associated with \spad{lp} whose coordinates are 
      ++ (real) strictly positive.
      ++ Moreover, if \spad{info?} is \spad{true} then some information is 
      ++ displayed during decomposition into regular chains.
      ++ If \spad{lextri?} is \spad{true} then the lexTriangular 
      ++ algorithm is called
      ++ from the \spadtype{LexTriangularPackage} constructor
      ++ (see zeroSetSplit from LexTriangularPackage(lp,false)).
      ++ Otherwise, the triangular decomposition is computed directly 
      ++ from the input
      ++ system by using the zeroSetSplit from \spadtype{RegularChain}.
      ++ WARNING. For each set of coordinates given by 
      ++ \spad{positiveSolve(lp,info?,lextri?)} 
      ++ the ordering of the indeterminates is reversed w.r.t. \spad{ls}.

    positiveSolve : (LP,B) -> List REALSOL
      ++ \spad{positiveSolve(lp)} returns the same as 
      ++ \spad{positiveSolve(lp,info?,false)}.

    positiveSolve : LP -> List REALSOL
      ++ \spad{positiveSolve(lp)} returns the same as 
      ++ \spad{positiveSolve(lp,false,false)}.

    squareFree : (TS) -> List ST
      ++ \spad{squareFree(ts)} returns the square-free factorization 
      ++ of \spad{ts}. Moreover, each factor is a Lazard triangular set 
      ++ and the decomposition 
      ++ is a Kalkbrener split of \spad{ts}, which is enough here for
      ++ the matter of solving zero-dimensional algebraic systems.
      ++ WARNING. \spad{ts} is not checked to be zero-dimensional.

    convert : Q -> Q2
      ++ \spad{convert(q)} converts \spad{q}.

    convert : P -> PRC
      ++ \spad{convert(p)} converts \spad{p}.

    convert : Q2 -> PRC
      ++ \spad{convert(q)} converts \spad{q}.

    convert : U -> URC
      ++ \spad{convert(u)} converts \spad{u}.

    convert : ST -> List Q2
      ++ \spad{convert(st)} returns the members of \spad{st}.

  CODE ==> add

     news: Symbol := last(ls2)$(List Symbol)
     newv: V2 := (variable(news)$V2)::V2
     newq: Q2 :=  newv :: Q2

     convert(q:Q):Q2 ==
       ground? q => (ground(q))::Q2
       q2: Q2 := 0
       while not ground?(q) repeat
         v: V := mvar(q)
         d: N := mdeg(q)
         v2: V2 := (variable(convert(v)@Symbol)$V2)::V2
         iq2: Q2 := convert(init(q))@Q2 
         lq2: Q2 := (v2 :: Q2)
         lq2 := lq2 ** d
         q2 := iq2 * lq2 + q2
         q := tail(q)
       q2 + (ground(q))::Q2

     squareFree(ts:TS):List(ST) == 
       irred?: Boolean := false
       st: ST := [[newq]$(List Q2)]      
       lq: List(Q2) := [convert(p)@Q2 for p in parts(ts)]
       lq := sort(infRittWu?,lq)
       toSee: List LQ2WT := []
       if irred?
         then
           lf := irreducibleFactors([first lq])$polsetpack
           lq := rest lq
           for f in lf repeat
             toSee := cons([cons(f,lq),st]$LQ2WT, toSee)
         else
           toSee := [[lq,st]$LQ2WT]
       toSave: List ST := []
       while not empty? toSee repeat
         lqwt := first toSee; toSee := rest toSee
         lq := lqwt.val; st := lqwt.tower
         empty? lq => 
           toSave := cons(st,toSave)
         q := first lq; lq := rest lq
         lsfqwt: List Q2WT := squareFreePart(q,st)$ST
         for sfqwt in lsfqwt repeat
           q := sfqwt.val; st := sfqwt.tower
           if not ground? init(q)
             then
               q := normalizedAssociate(q,st)$normpack
           newts := internalAugment(q,st)$ST      
           newlq := [remainder(q,newts).polnum for q in lq]
           toSee := cons([newlq,newts]$LQ2WT,toSee)
       toSave

     triangSolve(lp: LP, info?: B, lextri?: B): List TS ==
       lq: List(Q) := [convert(p)$Q for p in lp]
       lextri? => zeroSetSplit(lq,false)$lextripack
       zeroSetSplit(lq,true,info?)$TS

     triangSolve(lp: LP, info?: B): List TS == triangSolve(lp,info?,false)

     triangSolve(lp: LP): List TS == triangSolve(lp,false)

     convert(u: U): URC ==
       zero? u => 0
       ground? u => ((ground(u) :: K)::RC)::URC
       uu: URC := 0
       while not ground? u repeat
         uu := monomial((leadingCoefficient(u) :: K):: RC,degree(u)) + uu
         u := reductum u
       uu + ((ground(u) :: K)::RC)::URC

     coerceFromRtoRC(r:R): RC ==
       (r::K)::RC

     convert(p:P): PRC ==
       map(coerceFromRtoRC,p)$PolynomialFunctions2(R,RC)

     convert(q2:Q2): PRC ==
       p: P := coerce(q2)$Q2
       convert(p)@PRC
       
     convert(sts:ST): List Q2 ==
       lq2: List(Q2) := parts(sts)$ST
       lq2 := sort(infRittWu?,lq2)
       rest(lq2)

     realSolve(ts: TS): List REALSOL ==
       lsts: List ST := squareFree(ts)
       lr: REALSOL := []
       lv: List Symbol := []
       toSee := [[lr,lv,convert(sts)@(List Q2)]$WIP for sts in lsts]
       toSave: List REALSOL := []
       while not empty? toSee repeat
         wip := first toSee; toSee := rest toSee
         lr := wip.reals; lv := wip.vars; lq2 := wip.pols
         (empty? lq2) and (not empty? lr) => 
            toSave := cons(reverse(lr),toSave)
         q2 := first lq2; lq2 := rest lq2
         qrc := convert(q2)@PRC
         if not empty? lr 
           then
             for r in reverse(lr) for v in reverse(lv) repeat
               qrc := eval(qrc,v,r)
         lv := cons((mainVariable(qrc) :: Symbol),lv)
         urc: URC := univariate(qrc)@URC
         urcRoots := allRootsOf(urc)$RC
         for urcRoot in urcRoots repeat
           toSee := cons([cons(urcRoot,lr),lv,lq2]$WIP, toSee)
       toSave

     realSolve(lp: List(P), info?:Boolean, check?:Boolean, _
               lextri?: Boolean): List REALSOL  ==
       lts: List TS
       lq: List(Q) := [convert(p)$Q for p in lp]
       if lextri?
         then
           lts := zeroSetSplit(lq,false)$lextripack
         else
           lts := zeroSetSplit(lq,true,info?)$TS
       lsts:  List ST := []
       for ts in lts repeat 
         lsts := concat(squareFree(ts), lsts)
       lsts := removeSuperfluousQuasiComponents(lsts)$quasicomppack   
       lr: REALSOL := []
       lv: List Symbol := []
       toSee := [[lr,lv,convert(sts)@(List Q2)]$WIP for sts in lsts]
       toSave: List REALSOL := []
       while not empty? toSee repeat
         wip := first toSee; toSee := rest toSee
         lr := wip.reals; lv := wip.vars; lq2 := wip.pols
         (empty? lq2) and (not empty? lr) => 
            toSave := cons(reverse(lr),toSave)
         q2 := first lq2; lq2 := rest lq2
         qrc := convert(q2)@PRC
         if not empty? lr 
           then
             for r in reverse(lr) for v in reverse(lv) repeat
               qrc := eval(qrc,v,r)
         lv := cons((mainVariable(qrc) :: Symbol),lv)
         urc: URC := univariate(qrc)@URC
         urcRoots := allRootsOf(urc)$RC
         for urcRoot in urcRoots repeat
           toSee := cons([cons(urcRoot,lr),lv,lq2]$WIP, toSee)
       if check?
         then
           for p in lp repeat
             for realsol in toSave repeat
               prc: PRC := convert(p)@PRC
               for rr in realsol for symb in reverse(ls) repeat
                 prc := eval(prc,symb,rr)
               not zero? prc =>
                 error "realSolve$ZDSOLVE: bad result"
       toSave

     realSolve(lp: List(P), info?:Boolean, check?:Boolean): List REALSOL  ==
       realSolve(lp,info?,check?,false)
         
     realSolve(lp: List(P), info?:Boolean): List REALSOL  ==
       realSolve(lp,info?,false,false)

     realSolve(lp: List(P)): List REALSOL  ==
       realSolve(lp,false,false,false)

     positiveSolve(ts: TS): List REALSOL ==
       lsts: List ST := squareFree(ts)
       lr: REALSOL := []
       lv: List Symbol := []
       toSee := [[lr,lv,convert(sts)@(List Q2)]$WIP for sts in lsts]
       toSave: List REALSOL := []
       while not empty? toSee repeat
         wip := first toSee; toSee := rest toSee
         lr := wip.reals; lv := wip.vars; lq2 := wip.pols
         (empty? lq2) and (not empty? lr) => 
            toSave := cons(reverse(lr),toSave)
         q2 := first lq2; lq2 := rest lq2
         qrc := convert(q2)@PRC
         if not empty? lr 
           then
             for r in reverse(lr) for v in reverse(lv) repeat
               qrc := eval(qrc,v,r)
         lv := cons((mainVariable(qrc) :: Symbol),lv)
         urc: URC := univariate(qrc)@URC
         urcRoots := allRootsOf(urc)$RC
         for urcRoot in urcRoots repeat
           if positive? urcRoot
             then 
               toSee := cons([cons(urcRoot,lr),lv,lq2]$WIP, toSee)
       toSave

     positiveSolve(lp: List(P),info?:Boolean,lextri?: Boolean):List REALSOL  ==
       lts: List TS
       lq: List(Q) := [convert(p)$Q for p in lp]
       if lextri?
         then
           lts := zeroSetSplit(lq,false)$lextripack
         else
           lts := zeroSetSplit(lq,true,info?)$TS
       lsts:  List ST := []
       for ts in lts repeat 
         lsts := concat(squareFree(ts), lsts)
       lsts := removeSuperfluousQuasiComponents(lsts)$quasicomppack   
       lr: REALSOL := []
       lv: List Symbol := []
       toSee := [[lr,lv,convert(sts)@(List Q2)]$WIP for sts in lsts]
       toSave: List REALSOL := []
       while not empty? toSee repeat
         wip := first toSee; toSee := rest toSee
         lr := wip.reals; lv := wip.vars; lq2 := wip.pols
         (empty? lq2) and (not empty? lr) => 
            toSave := cons(reverse(lr),toSave)
         q2 := first lq2; lq2 := rest lq2
         qrc := convert(q2)@PRC
         if not empty? lr 
           then
             for r in reverse(lr) for v in reverse(lv) repeat
               qrc := eval(qrc,v,r)
         lv := cons((mainVariable(qrc) :: Symbol),lv)
         urc: URC := univariate(qrc)@URC
         urcRoots := allRootsOf(urc)$RC
         for urcRoot in urcRoots repeat
           if positive? urcRoot
             then 
               toSee := cons([cons(urcRoot,lr),lv,lq2]$WIP, toSee)
       toSave

     positiveSolve(lp: List(P), info?:Boolean): List REALSOL  ==
       positiveSolve(lp, info?, false)

     positiveSolve(lp: List(P)): List REALSOL  ==
       positiveSolve(lp, false, false)

     univariateSolve(ts: TS): List RUR ==
       toSee: List ST := squareFree(ts)
       toSave: List RUR := []
       for st in toSee repeat
         lus: List ST := rur(st,true)$rurpack 
         for us in lus repeat
           g: U  := univariate(select(us,newv)::Q2)$Q2
           lc: LP:=[convert(q2)@P for q2 in parts(collectUpper(us,newv)$ST)$ST]
           toSave := cons([g,lc]$RUR, toSave)
       toSave

     univariateSolve(lp: List(P), info?:Boolean, check?:Boolean, _
                     lextri?: Boolean): List RUR ==
       lts: List TS
       lq: List(Q) := [convert(p)$Q for p in lp]
       if lextri?
         then
           lts := zeroSetSplit(lq,false)$lextripack
         else
           lts := zeroSetSplit(lq,true,info?)$TS
       toSee:  List ST := []
       for ts in lts repeat 
         toSee := concat(squareFree(ts), toSee)
       toSee := removeSuperfluousQuasiComponents(toSee)$quasicomppack   
       toSave: List RUR := []
       if check?
         then
           lq2: List(Q2) := [convert(p)$Q2 for p in lp]
       for st in toSee repeat
         lus: List ST := rur(st,true)$rurpack 
         for us in lus repeat
            if check?
              then
                rems: List(Q2) := [removeZero(q2,us)$ST for q2 in lq2]
                not every?(zero?,rems) =>
                  output(st::OutputForm)$OutputPackage
                  output("Has a bad RUR component:")$OutputPackage
                  output(us::OutputForm)$OutputPackage
                  error "univariateSolve$ZDSOLVE: bad RUR"
            g: U  := univariate(select(us,newv)::Q2)$Q2
            lc: LP := _
              [convert(q2)@P for q2 in parts(collectUpper(us,newv)$ST)$ST]
            toSave := cons([g,lc]$RUR, toSave)
       toSave

     univariateSolve(lp: List(P), info?:Boolean, check?:Boolean): List RUR ==
       univariateSolve(lp,info?,check?,false)

     univariateSolve(lp: List(P), info?:Boolean): List RUR ==
       univariateSolve(lp,info?,false,false)

     univariateSolve(lp: List(P)): List RUR ==
       univariateSolve(lp,false,false,false)