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fix a bug in pivot_fixed_vars_from_basis

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Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
This commit is contained in:
Lev Nachmanson 2017-07-06 10:53:32 -07:00
parent 4c23527974
commit b21741cccd
2 changed files with 10 additions and 5 deletions
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1
src/util/lp/lp_core_solver_base.h
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@ -479,6 +479,7 @@ public:
void change_basis(unsigned entering, unsigned leaving) { void change_basis(unsigned entering, unsigned leaving) {
lean_assert(m_basis_heading[entering] < 0); lean_assert(m_basis_heading[entering] < 0);
lean_assert(m_basis_heading[leaving] >= 0);
int place_in_basis = m_basis_heading[leaving]; int place_in_basis = m_basis_heading[leaving];
int place_in_non_basis = - m_basis_heading[entering] - 1; int place_in_non_basis = - m_basis_heading[entering] - 1;

14
src/util/lp/lp_core_solver_base.hpp
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@ -925,7 +925,9 @@ template <typename T, typename X> void lp_core_solver_base<T, X>::transpose_row
} }
// j is the new basic column, j_basic - the leaving column // j is the new basic column, j_basic - the leaving column
template <typename T, typename X> bool lp_core_solver_base<T, X>::pivot_column_general(unsigned j, unsigned j_basic, indexed_vector<T> & w) { template <typename T, typename X> bool lp_core_solver_base<T, X>::pivot_column_general(unsigned j, unsigned j_basic, indexed_vector<T> & w) {
unsigned row_index = m_basis_heading[j_basic]; lean_assert(m_basis_heading[j] < 0);
lean_assert(m_basis_heading[j_basic] >= 0);
unsigned row_index = m_basis_heading[j_basic];
change_basis(j, j_basic); change_basis(j, j_basic);
if (m_settings.m_simplex_strategy == simplex_strategy_enum::lu) { if (m_settings.m_simplex_strategy == simplex_strategy_enum::lu) {
if (m_factorization->need_to_refactor()) { if (m_factorization->need_to_refactor()) {
@ -940,15 +942,16 @@ template <typename T, typename X> bool lp_core_solver_base<T, X>::pivot_column_g
return false; return false;
} }
} else { // the tableau case } else { // the tableau case
pivot_column_tableau(j, row_index); return pivot_column_tableau(j, row_index);
} }
return true;
} }
template <typename T, typename X> void lp_core_solver_base<T, X>::pivot_fixed_vars_from_basis() { template <typename T, typename X> void lp_core_solver_base<T, X>::pivot_fixed_vars_from_basis() {
// run over basis and non-basis at the same time // run over basis and non-basis at the same time
indexed_vector<T> w(m_basis.size()); // the buffer indexed_vector<T> w(m_basis.size()); // the buffer
unsigned i = 0; // points to basis unsigned i = 0; // points to basis
unsigned j = 0; // points to nonbasis unsigned j = 0; // points to nonbasis
for (; i < m_basis.size() && j < m_nbasis.size(); i++) { for (; i < m_basis.size() && j < m_nbasis.size(); i++) {
unsigned ii = m_basis[i]; unsigned ii = m_basis[i];
unsigned jj; unsigned jj;
@ -963,8 +966,9 @@ template <typename T, typename X> void lp_core_solver_base<T, X>::pivot_fixed_v
if (j >= m_nbasis.size()) if (j >= m_nbasis.size())
break; break;
j++; j++;
if (!pivot_column_general(jj, ii, w)) if (!pivot_column_general(jj, ii, w))
break; return; // total failure
break;
} }
} }
} }