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// Copyright 2005, Michael E. Stillman
#include "reducedgb-ZZ.hpp"
#include "monideal.hpp"
#include <functional>
#include <algorithm>
#include "text-io.hpp"
ReducedGB_ZZ::~ReducedGB_ZZ()
{
delete T;
ringtableZZ = 0;
}
ReducedGB_ZZ::ReducedGB_ZZ(GBRing *R0,
const PolynomialRing *originalR0,
const FreeModule *F0,
const FreeModule *Fsyz0)
: ReducedGB(R0, originalR0, F0, Fsyz0),
T(nullptr),
ringtableZZ(nullptr)
{
T = MonomialTableZZ::make(R0->n_vars());
if (originalR->is_quotient_ring())
ringtableZZ = originalR->get_quotient_MonomialTableZZ();
}
void ReducedGB_ZZ::set_gb(VECTOR(POLY) & polys0) {}
struct ReducedGB_ZZ_sorter : public std::binary_function<int, int, bool>
{
GBRing *R;
const FreeModule *F;
const VECTOR(POLY) & gb;
ReducedGB_ZZ_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;
int cmp = R->gbvector_compare(F, x, y);
if (cmp == LT) return true;
if (cmp == GT) return false;
// Now order them in ascending order on the coeff (which should always be
// POSITIVE).
return (mpz_cmp(x->coeff.get_mpz(), y->coeff.get_mpz()) < 0);
}
};
void ReducedGB_ZZ::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);
std::stable_sort(
positions.begin(), positions.end(), ReducedGB_ZZ_sorter(R, F, polys0));
// 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++)
{
gbvector *f = polys0[*i].f;
exponents e = R->exponents_make();
R->gbvector_get_lead_exponents(F, f, e);
if ((!ringtableZZ ||
!ringtableZZ->find_term_divisors(1, f->coeff.get_mpz(), e, 1)) &&
T->find_term_divisors(1, f->coeff.get_mpz(), 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.
if (h.f != 0 && mpz_sgn(h.f->coeff.get_mpz()) < 0)
{
R->gbvector_mult_by_coeff_to(h.f, globalZZ->minus_one());
R->gbvector_mult_by_coeff_to(h.fsyz, globalZZ->minus_one());
}
T->insert(h.f->coeff.get_mpz(), e, h.f->comp, INTSIZE(polys));
polys.push_back(h);
}
else
R->exponents_delete(e);
}
}
enum ReducedGB_ZZ::divisor_type ReducedGB_ZZ::find_divisor(exponents exp,
int comp,
int &result_loc)
{
int w = T->find_smallest_coeff_divisor(exp, comp); // gives smallest coeff
int r = -1;
if (ringtableZZ) r = ringtableZZ->find_smallest_coeff_divisor(exp, 1);
if (r < 0)
{
if (w < 0) return DIVISOR_NONE;
result_loc = w;
return DIVISOR_MODULE;
}
// r >= 0
if (w < 0)
{
result_loc = r;
return DIVISOR_RING;
}
// r >= 0, w >= 0
mpz_srcptr rc = originalR->quotient_gbvector(r)->coeff.get_mpz();
mpz_srcptr wc = polys[w].f->coeff.get_mpz();
if (mpz_cmpabs(rc, wc) > 0)
{
result_loc = w;
return DIVISOR_MODULE;
}
result_loc = r;
return DIVISOR_RING;
}
void ReducedGB_ZZ::remainder(POLY &f, bool use_denom, ring_elem &denom)
{
gbvector *zero = 0;
gbvector head;
gbvector *frem = &head;
frem->next = 0;
POLY h = f;
exponents EXP = ALLOCATE_EXPONENTS(R->exponent_byte_size());
gbvector *r;
POLY g;
while (!R->gbvector_is_zero(h.f))
{
int w;
R->gbvector_get_lead_exponents(F, h.f, EXP);
int x = h.f->comp;
enum divisor_type typ = find_divisor(EXP, x, w);
switch (typ)
{
case DIVISOR_RING:
r = const_cast<gbvector *>(originalR->quotient_gbvector(w));
if (R->gbvector_reduce_lead_term_ZZ(F, Fsyz, h.f, zero, r, zero))
continue;
break;
case DIVISOR_MODULE:
g = polys[w];
if (R->gbvector_reduce_lead_term_ZZ(
F, Fsyz, h.f, h.fsyz, g.f, g.fsyz))
continue;
break;
case DIVISOR_NONE:
break;
}
frem->next = h.f;
frem = frem->next;
h.f = h.f->next;
frem->next = 0;
}
h.f = head.next;
f.f = h.f;
originalR->get_quotient_info()->gbvector_normal_form(Fsyz, h.fsyz);
f.fsyz = h.fsyz;
}
void ReducedGB_ZZ::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());
gbvector *r;
POLY g;
while (!R->gbvector_is_zero(h))
{
int w;
R->gbvector_get_lead_exponents(F, h, EXP);
int x = h->comp;
enum divisor_type typ = find_divisor(EXP, x, w);
switch (typ)
{
case DIVISOR_RING:
r = const_cast<gbvector *>(originalR->quotient_gbvector(w));
if (R->gbvector_reduce_lead_term_ZZ(F, Fsyz, h, zero, r, zero))
continue;
break;
case DIVISOR_MODULE:
g = polys[w];
if (M2_gbTrace >= 4)
{
buffer o;
R->gbvector_text_out(o, F, h);
o << newline << " divisor " << w << " is ";
R->gbvector_text_out(o, F, g.f);
o << newline;
emit(o.str());
}
if (R->gbvector_reduce_lead_term_ZZ(F, Fsyz, h, zero, g.f, zero))
continue;
break;
case DIVISOR_NONE:
break;
}
frem->next = h;
frem = frem->next;
h = h->next;
frem->next = 0;
}
h = head.next;
f = h;
}
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End:
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