schur-poly-heap.hpp

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// Copyright 1996-2011 Michael E. Stillman
 
#ifndef _schur_poly_heap_hpp_
#define _schur_poly_heap_hpp_

 
class schur_poly_heap : public our_new_delete
{
  ring_elem heap[GEOHEAP_SIZE];
  const SchurRing2 *S;
  int top_of_heap;
 
  void add_to(ring_elem &a, ring_elem &b);
 
 public:
  schur_poly_heap(const SchurRing2 *S0);
  ~schur_poly_heap() { /* nothing */}
 
  void add(ring_elem p);
 
  ring_elem
  value();  // Returns the linearized value, and resets the schur_poly_heap.
 
  ring_elem debug_list(int i)
  {
    return heap[i];
  }  // DO NOT USE, except for debugging purposes!
};
 
inline void schur_poly_heap::add_to(ring_elem &a, ring_elem &b)
{
  ring_elem c = S->add(a, b);
  a = c;
  b = S->zero();
}
 
inline schur_poly_heap::schur_poly_heap(const SchurRing2 *S0)
    : S(S0), top_of_heap(-1)
{
  int i;
  for (i = 0; i < GEOHEAP_SIZE; i++) heap[i] = S->zero();
}
 
inline void schur_poly_heap::add(ring_elem p)
{
  size_t len = S->size(p);
  int i = 0;
  while (len >= heap_size[i]) i++;
  add_to(heap[i], p);
  len = S->size(heap[i]);
  while (len >= heap_size[i])
    {
      i++;
      add_to(heap[i], heap[i - 1]);
      len = S->size(heap[i]);
    }
  if (i > top_of_heap) top_of_heap = i;
}
 
inline ring_elem schur_poly_heap::value()
{
  ring_elem result = S->zero();
  for (int i = 0; i <= top_of_heap; i++)
    {
      if (S->size(heap[i]) == 0) continue;
      add_to(result, heap[i]);
    }
  top_of_heap = -1;
  return result;
}
 
#endif