promote() [4/4]

template<typename RingType>

bool M2::ConcreteRing< RingType >::promote ( const Ring * S, const ring_elem f, ring_elem & result ) const

virtual

If there is a "natural" map S --> R=this, where f is an element of S , then result is set to the image of f, and true is returned. Otherwise, false is returned.

The map must one-step, e.g. for k --> k[x] --> k[x][y], promotion must be done with two consecutive calls to promote(with different arguments). Examples of natural maps: ZZ --> R, for any R QQ --> RR --> CC ZZ --> ZZ/p ZZ/p --> GF(p^n) GF(p^m) --> GF(p^n), where m|n A --> A[vars]/I A[vars]/J --> A[vars]/I (assumption: I contains J).

Implements Ring.

Definition at line 663 of file aring-glue.hpp.

{
  const Ring *S = this;
  //    fprintf(stderr, "calling promote\n");
  namespace RP = RingPromoter;
  if (R == globalZZ)
    {
      resultS = S->from_int(fR.get_mpz());
      return true;
    }
  if (R == S)
    {
      resultS = copy(fR);
      return true;
    }
  switch (R->ringID())
    {
      case M2::ring_ZZp:
        switch (S->ringID())
          {
            case M2::ring_ZZp:
              return false;
            case M2::ring_ZZpFfpack:
              return RP::promoter<ARingZZp, ARingZZpFFPACK>(R, S, fR, resultS);
            default:
              return false;
          }
        break;
      case M2::ring_ZZpFfpack:
        switch (S->ringID())
          {
            case M2::ring_ZZp:
              return RP::promoter<ARingZZpFFPACK, ARingZZp>(R, S, fR, resultS);
            case M2::ring_ZZpFfpack:
              return RP::promoter<ARingZZpFFPACK, ARingZZpFFPACK>(
                  R, S, fR, resultS);
            default:
              return false;
          }
      case M2::ring_QQ:
        switch (S->ringID())
          {
            case M2::ring_RR:
              return RP::promoter<ARingQQ, ARingRR>(R, S, fR, resultS);
            case M2::ring_RRR:
              return RP::promoter<ARingQQ, ARingRRR>(R, S, fR, resultS);
            case M2::ring_RRi:
              return RP::promoter<ARingQQ, ARingRRi>(R, S, fR, resultS);
            case M2::ring_CC:
              return RP::promoter<ARingQQ, ARingCC>(R, S, fR, resultS);
            case M2::ring_CCC:
              return RP::promoter<ARingQQ, ARingCCC>(R, S, fR, resultS);
            case M2::ring_CCi:
             return RP::promoter<ARingQQ, ARingCCi>(R, S, fR, resultS);
            default:
              return false;
          }
      case M2::ring_RR:
        switch (S->ringID())
          {
            case M2::ring_RR:
              return RP::promoter<ARingRR, ARingRR>(R, S, fR, resultS);
            case M2::ring_RRR:
              return RP::promoter<ARingRR, ARingRRR>(R, S, fR, resultS);
            case M2::ring_RRi:
              return RP::promoter<ARingRR, ARingRRi>(R, S, fR, resultS);
            case M2::ring_CC:
              return RP::promoter<ARingRR, ARingCC>(R, S, fR, resultS);
            case M2::ring_CCC:
              return RP::promoter<ARingRR, ARingCCC>(R, S, fR, resultS);
            case M2::ring_CCi:
              return RP::promoter<ARingRR, ARingCCi>(R, S, fR, resultS);
            default:
              return false;
          }
      case M2::ring_RRR:
        switch (S->ringID())
          {
            case M2::ring_RR:
              return RP::promoter<ARingRRR, ARingRR>(R, S, fR, resultS);
            case M2::ring_RRR:
              return RP::promoter<ARingRRR, ARingRRR>(R, S, fR, resultS);
            case M2::ring_RRi:
              return RP::promoter<ARingRRR, ARingRRi>(R, S, fR, resultS);
            case M2::ring_CC:
              return RP::promoter<ARingRRR, ARingCC>(R, S, fR, resultS);
            case M2::ring_CCC:
              return RP::promoter<ARingRRR, ARingCCC>(R, S, fR, resultS);
            case M2::ring_CCi:
                return RP::promoter<ARingRRR, ARingCCi>(R, S, fR, resultS);
            default:
              return false;
          }
      case M2::ring_RRi:
        switch (S->ringID())
           {
              case M2::ring_RR:
                return RP::promoter<ARingRRi, ARingRR>(R, S, fR, resultS);
              case M2::ring_RRR:
                return RP::promoter<ARingRRi, ARingRRR>(R, S, fR, resultS);
              case M2::ring_RRi:
                return RP::promoter<ARingRRi, ARingRRi>(R, S, fR, resultS);
               case M2::ring_CCi:
                   return RP::promoter<ARingRRi,ARingCCi>(R, S, fR, resultS);
              default:
                 return false;
          }
      case M2::ring_CC:
        switch (S->ringID())
          {
            case M2::ring_CC:
              return RP::promoter<ARingCC, ARingCC>(R, S, fR, resultS);
            case M2::ring_CCC:
              return RP::promoter<ARingCC, ARingCCC>(R, S, fR, resultS);
            case M2::ring_CCi:
              return RP::promoter<ARingCC, ARingCCi>(R, S, fR, resultS);
            default:
              return false;
          }
      case M2::ring_CCC:
        switch (S->ringID())
          {
            case M2::ring_CCC:
              return RP::promoter<ARingCCC, ARingCCC>(R, S, fR, resultS);
            case M2::ring_CC:
              return RP::promoter<ARingCCC, ARingCC>(R, S, fR, resultS);
            case M2::ring_CCi:
              return RP::promoter<ARingCCC, ARingCCi>(R, S, fR, resultS);
            default:
              return false;
          }
        case M2::ring_CCi:
          switch (S->ringID())
             {
                 case M2::ring_CCi:
                   return RP::promoter<ARingCCi, ARingCCi>(R, S, fR, resultS);
                default:
                   return false;
            }
      default:
        break;
    };
  return false;
}

References copy(), Ring::from_int(), ring_elem::get_mpz(), globalZZ, R, Ring::Ring(), M2::ring_CC, M2::ring_CCC, M2::ring_CCi, M2::ring_QQ, M2::ring_RR, M2::ring_RRi, M2::ring_RRR, M2::ring_ZZp, M2::ring_ZZpFfpack, and Ring::ringID().