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// Copyright 2005, Michael E. Stillman
#include "reducedgb-field.hpp"
#include "monideal.hpp"
#include <functional>
#include <algorithm>
ReducedGB_Field::~ReducedGB_Field()
{
delete T;
Rideal = 0;
}
void ReducedGB_Field::set_gb(VECTOR(POLY) & polys0) {}
struct ReducedGB_Field_sorter : public std::binary_function<int, int, bool>
{
GBRing *R;
const FreeModule *F;
const VECTOR(POLY) & gb;
ReducedGB_Field_sorter(GBRing *R0,
const FreeModule *F0,
const VECTOR(POLY) & gb0)
: R(R0), F(F0), gb(gb0)
{
}
bool operator()(int xx, int yy)
{
gbvector *x = gb[xx].f;
gbvector *y = gb[yy].f;
return R->gbvector_compare(F, x, y) == LT;
}
};
ReducedGB_Field::ReducedGB_Field(GBRing *R0,
const PolynomialRing *originalR0,
const FreeModule *F0,
const FreeModule *Fsyz0)
: ReducedGB(R0, originalR0, F0, Fsyz0), T(nullptr), Rideal(nullptr)
{
T = MonomialTable::make(R0->n_vars());
if (originalR->is_quotient_ring())
Rideal = originalR->get_quotient_monomials();
}
void ReducedGB_Field::minimalize(const VECTOR(POLY) & polys0, bool auto_reduced)
// I have to decide: does this ADD to the existing set?
{
// First sort these elements via increasing lex order (or monomial order?)
// Next insert minimal elements into T, and polys
VECTOR(int) positions;
positions.reserve(polys0.size());
for (int i = 0; i < polys0.size(); i++) positions.push_back(i);
// displayElements("-- before sort --", R, polys0, [](auto& g) { return g.f;
// } );
std::stable_sort(
positions.begin(), positions.end(), ReducedGB_Field_sorter(R, F, polys0));
// VECTOR(gbvector*) sorted_elements_debug_only;
// for (int i=0; i<positions.size(); i++)
// sorted_elements_debug_only.push_back(polys0[positions[i]].f);
// displayElements("-- after sort --", R, sorted_elements_debug_only,
// [](auto& g) { return g; } );
// Now loop through each element, and see if the lead monomial is in T.
// If not, add it in , and place element into 'polys'.
for (VECTOR(int)::iterator i = positions.begin(); i != positions.end(); i++)
{
Bag *not_used;
gbvector *f = polys0[*i].f;
exponents e = R->exponents_make();
R->gbvector_get_lead_exponents(F, f, e);
if ((!Rideal || !Rideal->search_expvector(e, not_used)) &&
T->find_divisors(1, e, f->comp) == 0)
{
// Keep this element
POLY h;
ring_elem junk;
h.f = R->gbvector_copy(f);
h.fsyz = R->gbvector_copy(polys0[*i].fsyz);
if (auto_reduced) remainder(h, false, junk); // This auto-reduces h.
R->gbvector_remove_content(h.f, h.fsyz);
T->insert(e, f->comp, INTSIZE(polys));
polys.push_back(h);
}
else
R->exponents_delete(e);
}
}
void ReducedGB_Field::remainder(POLY &f, bool use_denom, ring_elem &denom)
{
gbvector head;
gbvector *frem = &head;
frem->next = 0;
POLY h = f;
exponents EXP = ALLOCATE_EXPONENTS(R->exponent_byte_size());
while (!R->gbvector_is_zero(h.f))
{
R->gbvector_get_lead_exponents(F, h.f, EXP);
int x = h.f->comp;
Bag *b;
if (Rideal != 0 && Rideal->search_expvector(EXP, b))
{
const gbvector *g = originalR->quotient_gbvector(b->basis_elem());
R->gbvector_reduce_lead_term(
F, Fsyz, head.next, h.f, h.fsyz, g, 0, use_denom, denom);
}
else
{
int w = T->find_divisor(EXP, x);
if (w >= 0)
{
POLY g = polys[w];
R->gbvector_reduce_lead_term(F,
Fsyz,
head.next,
h.f,
h.fsyz,
g.f,
g.fsyz,
use_denom,
denom);
}
else
{
frem->next = h.f;
frem = frem->next;
h.f = h.f->next;
frem->next = 0;
}
}
}
h.f = head.next;
// R->gbvector_remove_content(h.f, h.fsyz, use_denom, denom);
f.f = h.f;
originalR->get_quotient_info()->gbvector_normal_form(
Fsyz, h.fsyz, use_denom, denom);
f.fsyz = h.fsyz;
}
void ReducedGB_Field::remainder(gbvector *&f, bool use_denom, ring_elem &denom)
{
gbvector *zero = 0;
gbvector head;
gbvector *frem = &head;
frem->next = 0;
gbvector *h = f;
exponents EXP = ALLOCATE_EXPONENTS(R->exponent_byte_size());
while (!R->gbvector_is_zero(h))
{
R->gbvector_get_lead_exponents(F, h, EXP);
int x = h->comp;
Bag *b;
if (Rideal != 0 && Rideal->search_expvector(EXP, b))
{
const gbvector *g = originalR->quotient_gbvector(b->basis_elem());
R->gbvector_reduce_lead_term(
F, Fsyz, head.next, h, zero, g, zero, use_denom, denom);
}
else
{
int w = T->find_divisor(EXP, x);
if (w < 0)
{
frem->next = h;
frem = frem->next;
h = h->next;
frem->next = 0;
}
else
{
POLY g = polys[w];
R->gbvector_reduce_lead_term(
F, Fsyz, head.next, h, zero, g.f, zero, use_denom, denom);
}
}
}
h = head.next;
// R->gbvector_remove_content(h, 0, use_denom, denom);
f = h;
}
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End:
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