/// <summary>
/// Replace all occurrences of oldVar with expr, and update column cross indices
/// oldVar should now be a basic variable.
/// </summary>
protected void SubstituteOut(ClAbstractVariable oldVar, ClLinearExpression expr)
{
var varset = _columns[oldVar];
foreach (var v in varset)
{
var row = _rows[v];
row.SubstituteOut(oldVar, expr, v, this);
if (v.IsRestricted && row.Constant < 0.0)
{
InfeasibleRows.Add(v);
}
}
if (oldVar.IsExternal)
{
ExternalRows.Add((ClVariable)oldVar);
ExternalParametricVars.Remove((ClVariable)oldVar);
}
_columns.Remove(oldVar);
}
/// <summary>
/// Remove v from the tableau -- remove the column cross indices for v
/// and remove v from every expression in rows in which v occurs
/// </summary>
protected void RemoveColumn(ClAbstractVariable var)
{
// remove the rows with the variables in varset
HashSet <ClAbstractVariable> rows;
if (_columns.TryGetValue(var, out rows))
{
_columns.Remove(var);
foreach (var expr in rows.Select(clv => _rows[clv]))
{
expr.Terms.Remove(var);
}
}
if (var.IsExternal)
{
ExternalRows.Remove((ClVariable)var);
ExternalParametricVars.Remove((ClVariable)var);
}
}