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https://github.com/Z3Prover/z3
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95 lines
2.3 KiB
C++
95 lines
2.3 KiB
C++
/*++
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Copyright (c) 2017 Microsoft Corporation
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Module Name:
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<name>
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Abstract:
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<abstract>
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Author:
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Lev Nachmanson (levnach)
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Revision History:
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--*/
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#include "math/lp/random_updater.h"
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#include "math/lp/static_matrix.h"
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#include "math/lp/lar_solver.h"
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#include "util/vector.h"
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namespace lp {
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random_updater::random_updater(
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lar_solver & lar_solver,
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const vector<unsigned> & column_indices) :
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m_lar_solver(lar_solver),
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m_range(100000) {
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for (unsigned j : column_indices)
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add_column_to_sets(j);
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}
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bool random_updater::shift_var(unsigned v) {
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return m_lar_solver.get_int_solver()->shift_var(v, m_range);
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}
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bool random_updater::random_shift_var(unsigned j) {
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if (m_lar_solver.A_r().m_columns.size() >= 50) {
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return false;
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}
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return shift_var(j);
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}
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void random_updater::update() {
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for (auto j : m_var_set) {
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if (m_var_set.size() <= m_values.size()) {
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break; // we are done
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}
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auto old_x = m_lar_solver.get_column_value(j);
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if (random_shift_var(j)) {
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remove_value(old_x);
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add_value(m_lar_solver.get_column_value(j));
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}
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}
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}
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void random_updater::add_value(const numeric_pair<mpq>& v) {
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auto it = m_values.find(v);
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if (it == m_values.end()) {
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m_values[v] = 1;
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} else {
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it->second++;
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}
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}
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void random_updater::remove_value(const numeric_pair<mpq>& v) {
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std::unordered_map<numeric_pair<mpq>, unsigned>::iterator it = m_values.find(v);
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lp_assert(it != m_values.end());
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it->second--;
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if (it->second == 0)
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m_values.erase((std::unordered_map<numeric_pair<mpq>, unsigned>::const_iterator)it);
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}
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void random_updater::add_column_to_sets(unsigned j) {
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if (m_lar_solver.get_core_solver().m_r_heading[j] < 0) {
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m_var_set.insert(j);
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add_value(m_lar_solver.get_core_solver().m_r_x[j]);
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} else {
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unsigned row = m_lar_solver.get_core_solver().m_r_heading[j];
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for (auto & row_c : m_lar_solver.get_core_solver().m_r_A.m_rows[row]) {
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unsigned cj = row_c.var();
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if (m_lar_solver.get_core_solver().m_r_heading[cj] < 0) {
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m_var_set.insert(cj);
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add_value(m_lar_solver.get_core_solver().m_r_x[cj]);
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}
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}
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}
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}
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}
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