monomialOrderingToMatrix()

bool monomialOrderingToMatrix ( const struct MonomialOrdering & mo, std::vector< int > & mat, bool & base_is_revlex, int & component_direction, int & component_is_before_row )

extern

Definition at line 861 of file monomial-ordering.cpp.

{
  // a false return value means an error has occurred.
  int nvars = rawNumberOfVariables(&mo);
  base_is_revlex = true;
  enum LastBlock { LEX, REVLEX, WEIGHTS, NONE };
  LastBlock last = NONE;
  int nwts = 0;  // local var used in MO_WEIGHTS section
  int nrows = 0;
  int firstvar = 0;
  component_direction = 0;
  component_is_before_row =
      -2;                   // what should the default value be?  Probably: -1.
  size_t last_element = 0;  // The vector 'mat' will be resized back to this
                            // value if the last part of the order is lex or
                            // revlex.
  for (int i = 0; i < mo.len; i++)
    {
      mon_part p = mo.array[i];
      switch (p->type)
        {
          case MO_LEX:
          case MO_LEX2:
          case MO_LEX4:
            // printf("lex %d\n", p->nvars);
            last_element = mat.size();
            for (int j = 0; j < p->nvars; j++)
              {
                write_row(mat, nvars, firstvar + j, 1);
              }
            last = LEX;
            firstvar += p->nvars;
            nrows += p->nvars;
            break;
          case MO_GREVLEX:
          case MO_GREVLEX2:
          case MO_GREVLEX4:
            // printf("grevlex %d %ld\n", p->nvars, p->wts);
            write_weights(mat, nvars, firstvar, p->wts, p->nvars);
            last_element = mat.size();
            for (int j = p->nvars - 1; j >= 1; --j)
              {
                write_row(mat, nvars, firstvar + j, -1);
              }
            last = REVLEX;
            firstvar += p->nvars;
            nrows += p->nvars;
            break;
          case MO_GREVLEX_WTS:
          case MO_GREVLEX2_WTS:
          case MO_GREVLEX4_WTS:
            // printf("grevlex_wts %d %ld\n", p->nvars, p->wts);
            write_weights(mat, nvars, firstvar, p->wts, p->nvars);
            last_element = mat.size();
            for (int j = p->nvars - 1; j >= 1; --j)
              {
                write_row(mat, nvars, firstvar + j, -1);
              }
            last = REVLEX;
            firstvar += p->nvars;
            nrows += p->nvars;
            break;
          case MO_REVLEX:
            // printf("revlex %d\n", p->nvars);
            last_element = mat.size();
            for (int j = p->nvars - 1; j >= 0; --j)
              {
                write_row(mat, nvars, firstvar + j, -1);
              }
            last = REVLEX;
            firstvar += p->nvars;
            nrows += p->nvars;
            break;
          case MO_WEIGHTS:
            // printf("matsize= %d weights %d p->wts=%lu\n", mat.size(),
            // p->nvars, p->wts);
            nwts = (p->nvars > nvars ? nvars : p->nvars);
            write_weights(mat, nvars, 0, p->wts, nwts);
            nrows++;
            last_element = mat.size();
            last = WEIGHTS;
            break;
          case MO_LAURENT:
          case MO_LAURENT_REVLEX:
          case MO_NC_LEX:
            return false;
            break;
          case MO_POSITION_UP:
            component_direction = 1;
            component_is_before_row = nrows;
            break;
          case MO_POSITION_DOWN:
            component_direction = -1;
            component_is_before_row = nrows;
            break;
          default:
            // DO nothing
            break;
        }
    }
  if (last == LEX)
    {
      // last block was lex, so use lex tie-breaker
      mat.resize(last_element);
      if (nrows == component_is_before_row) component_is_before_row = -1;
      base_is_revlex = false;
    }
  else if (last == REVLEX)
    {
      // last block was revlex, so use revlex tie-breaker
      if (nrows == component_is_before_row) component_is_before_row = -1;
      mat.resize(last_element);
    }
  else
    {
      // last block is a weight vector, so use revlex as the tie-breaker.
      // nothing to change here.
    }
  return true;
}

References MonomialOrdering::array, MonomialOrdering::len, MO_GREVLEX, MO_GREVLEX2, MO_GREVLEX2_WTS, MO_GREVLEX4, MO_GREVLEX4_WTS, MO_GREVLEX_WTS, MO_LAURENT, MO_LAURENT_REVLEX, MO_LEX, MO_LEX2, MO_LEX4, MO_NC_LEX, MO_POSITION_DOWN, MO_POSITION_UP, MO_REVLEX, MO_WEIGHTS, mon_part::nvars, p, rawNumberOfVariables(), write_row(), and write_weights().

Referenced by MonomialInfo::MonomialInfo(), and rawMGB().