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avoid big pivots

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2020-04-11 11:49:25 -07:00
parent 20d72e5d97
commit 38c73090d8
2 changed files with 60 additions and 55 deletions
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18
src/math/lp/lp_primal_core_solver.h
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@ -280,8 +280,8 @@ public:
// a short row produces short infeasibility explanation and benefits at least one pivot operation // a short row produces short infeasibility explanation and benefits at least one pivot operation
int choice = -1; int choice = -1;
int nchoices = 0; int nchoices = 0;
unsigned num_of_non_free_basics = 1000000; unsigned prev_damage = UINT_MAX;
unsigned len = 100000000; unsigned len = UINT_MAX;
unsigned bj = this->m_basis[i]; unsigned bj = this->m_basis[i];
bool bj_needs_to_grow = needs_to_grow(bj); bool bj_needs_to_grow = needs_to_grow(bj);
for (unsigned k = 0; k < this->m_A.m_rows[i].size(); k++) { for (unsigned k = 0; k < this->m_A.m_rows[i].size(); k++) {
@ -296,14 +296,18 @@ public:
if (!monoid_can_increase(rc)) if (!monoid_can_increase(rc))
continue; continue;
} }
unsigned damage = get_number_of_basic_vars_that_might_become_inf(j); unsigned damage = numeric_traits<T>::is_big(rc.coeff())? prev_damage:
if (damage < num_of_non_free_basics) { get_number_of_basic_vars_that_might_become_inf(j);
num_of_non_free_basics = damage; if (damage < prev_damage) {
prev_damage = damage;
len = this->m_A.m_columns[j].size(); len = this->m_A.m_columns[j].size();
choice = k; choice = k;
nchoices = 1; nchoices = 1;
} else if (damage == num_of_non_free_basics && } else if (damage == prev_damage
this->m_A.m_columns[j].size() <= len && (this->m_settings.random_next() % (++nchoices))) { &&
this->m_A.m_columns[j].size() <= len
&&
(this->m_settings.random_next() % (++nchoices))) {
choice = k; choice = k;
len = this->m_A.m_columns[j].size(); len = this->m_A.m_columns[j].size();
} }

3
src/math/lp/numeric_pair.h
View file

@ -82,6 +82,7 @@ template <> class numeric_traits<double> {
static double from_string(std::string const & str) { return atof(str.c_str()); } static double from_string(std::string const & str) { return atof(str.c_str()); }
static bool is_pos(const double & d) {return d > 0.0;} static bool is_pos(const double & d) {return d > 0.0;}
static bool is_neg(const double & d) {return d < 0.0;} static bool is_neg(const double & d) {return d < 0.0;}
static bool is_big(const double & d) { return false; }
}; };
template<> template<>
@ -97,13 +98,13 @@ template <> class numeric_traits<double> {
static bool is_pos(const rational & d) {return d.is_pos();} static bool is_pos(const rational & d) {return d.is_pos();}
static bool is_neg(const rational & d) {return d.is_neg();} static bool is_neg(const rational & d) {return d.is_neg();}
static bool is_int(const rational & d) {return d.is_int();} static bool is_int(const rational & d) {return d.is_int();}
static bool is_big(const rational & d) {return d.is_big();}
static mpq ceil_ratio(const mpq & a, const mpq & b) { static mpq ceil_ratio(const mpq & a, const mpq & b) {
return ceil(a / b); return ceil(a / b);
} }
static mpq floor_ratio(const mpq & a, const mpq & b) { static mpq floor_ratio(const mpq & a, const mpq & b) {
return floor(a / b); return floor(a / b);
} }
}; };
#endif #endif