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/********************* */
/*! \file tableau.cpp
** \verbatim
** Original author: taking
** Major contributors: none
** Minor contributors (to current version): none
** This file is part of the CVC4 prototype.
** Copyright (c) 2009, 2010 The Analysis of Computer Systems Group (ACSys)
** Courant Institute of Mathematical Sciences
** New York University
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief [[ Add one-line brief description here ]]
**
** [[ Add lengthier description here ]]
** \todo document this file
**/
#include "theory/arith/tableau.h"
using namespace CVC4;
using namespace CVC4::theory;
using namespace CVC4::theory::arith;
Row::Row(ArithVar basic,
const std::vector< Rational >& coefficients,
const std::vector< ArithVar >& variables):
d_x_i(basic),
d_coeffs(){
Assert(coefficients.size() == variables.size() );
std::vector<Rational>::const_iterator coeffIter = coefficients.begin();
std::vector<Rational>::const_iterator coeffEnd = coefficients.end();
std::vector<ArithVar>::const_iterator varIter = variables.begin();
for(; coeffIter != coeffEnd; ++coeffIter, ++varIter){
const Rational& coeff = *coeffIter;
ArithVar var_i = *varIter;
Assert(var_i != d_x_i);
Assert(!has(var_i));
Assert(coeff != Rational(0,1));
d_coeffs[var_i] = coeff;
Assert(d_coeffs[var_i] != Rational(0,1));
}
}
void Row::subsitute(Row& row_s){
ArithVar x_s = row_s.basicVar();
Assert(has(x_s));
Assert(x_s != d_x_i);
Rational zero(0,1);
Rational a_rs = lookup(x_s);
Assert(a_rs != zero);
d_coeffs.erase(x_s);
for(iterator iter = row_s.begin(), iter_end = row_s.end();
iter != iter_end; ++iter){
ArithVar x_j = iter->first;
Rational a_sj = iter->second;
a_sj *= a_rs;
CoefficientTable::iterator coeff_iter = d_coeffs.find(x_j);
if(coeff_iter != d_coeffs.end()){
coeff_iter->second += a_sj;
if(coeff_iter->second == zero){
d_coeffs.erase(coeff_iter);
}
}else{
d_coeffs.insert(std::make_pair(x_j,a_sj));
}
}
}
void Row::pivot(ArithVar x_j){
Rational negInverseA_rs = -(lookup(x_j).inverse());
d_coeffs[d_x_i] = Rational(Integer(-1));
d_coeffs.erase(x_j);
d_x_i = x_j;
for(iterator nonbasicIter = begin(), nonbasicIter_end = end();
nonbasicIter != nonbasicIter_end; ++nonbasicIter){
nonbasicIter->second *= negInverseA_rs;
}
}
void Row::printRow(){
Debug("tableau") << d_x_i << " ";
for(iterator nonbasicIter = d_coeffs.begin();
nonbasicIter != d_coeffs.end();
++nonbasicIter){
ArithVar nb = nonbasicIter->first;
Debug("tableau") << "{" << nb << "," << d_coeffs[nb] << "}";
}
Debug("tableau") << std::endl;
}
void Tableau::addRow(ArithVar basicVar,
const std::vector<Rational>& coeffs,
const std::vector<ArithVar>& variables){
Assert(coeffs.size() == variables.size());
Assert(d_basicManager.isBasic(basicVar));
//The new basic variable cannot already be a basic variable
Assert(!isActiveBasicVariable(basicVar));
d_activeBasicVars.insert(basicVar);
Row* row_current = new Row(basicVar,coeffs,variables);
d_rowsTable[basicVar] = row_current;
//A variable in the row may have been made non-basic already.
//If this is the case we fake pivoting this variable
std::vector<Rational>::const_iterator coeffsIter = coeffs.begin();
std::vector<Rational>::const_iterator coeffsEnd = coeffs.end();
std::vector<ArithVar>::const_iterator varsIter = variables.begin();
for( ; coeffsIter != coeffsEnd; ++coeffsIter, ++ varsIter){
ArithVar var = *varsIter;
if(d_basicManager.isBasic(var)){
if(!isActiveBasicVariable(var)){
reinjectBasic(var);
}
Assert(isActiveBasicVariable(var));
Row* row_var = lookup(var);
row_current->subsitute(*row_var);
}
}
}
void Tableau::pivot(ArithVar x_r, ArithVar x_s){
Assert(d_basicManager.isBasic(x_r));
Assert(!d_basicManager.isBasic(x_s));
Row* row_s = lookup(x_r);
Assert(row_s->has(x_s));
//Swap x_r and x_s in d_activeRows
d_rowsTable[x_s] = row_s;
d_rowsTable[x_r] = NULL;
d_activeBasicVars.erase(x_r);
d_basicManager.makeNonbasic(x_r);
d_activeBasicVars.insert(x_s);
d_basicManager.makeBasic(x_s);
row_s->pivot(x_s);
for(ArithVarSet::iterator basicIter = begin(), endIter = end();
basicIter != endIter; ++basicIter){
ArithVar basic = *basicIter;
Row* row_k = lookup(basic);
if(row_k->has(x_s)){
d_activityMonitor.increaseActivity(basic, 30);
row_k->subsitute(*row_s);
}
}
}
void Tableau::printTableau(){
Debug("tableau") << "Tableau::d_activeRows" << endl;
typedef RowsTable::iterator table_iter;
for(table_iter rowIter = d_rowsTable.begin(), end = d_rowsTable.end();
rowIter != end; ++rowIter){
Row* row_k = *rowIter;
if(row_k != NULL){
row_k->printRow();
}
}
}
void Tableau::updateRow(Row* row){
for(Row::iterator i=row->begin(), endIter = row->end(); i != endIter; ){
ArithVar var = i->first;
++i;
if(d_basicManager.isBasic(var)){
Row* row_var = isActiveBasicVariable(var) ? lookup(var) : lookupEjected(var);
Assert(row_var != row);
row->subsitute(*row_var);
i = row->begin();
endIter = row->end();
}
}
}
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