internal static void UpdateNegativeRHSValues(this ISimplexModel model)
{
//1) Check and update Right Hand Side- RHS value for positive
foreach (Subject constarint in model.Subjects)
{
if (constarint.RightHandValue < 0)
{
constarint.RightHandValue *= -1;
foreach (Term term in constarint.Terms)
{
term.Factor *= -1;
}
if (constarint.Equality == EquailtyType.GreaterEquals)
{
constarint.Equality = EquailtyType.LessEquals;
}
else if (constarint.Equality == EquailtyType.LessEquals)
{
constarint.Equality = EquailtyType.GreaterEquals;
}
//nothing to do for equal, equal is equal
}
}
}
public static TestMessage CheckBFS(this ISimplexModel model)
{
TestMessage retval = new TestMessage()
{
Exception = null, Message = string.Empty
};
//first, update rhs values for equality direction control
UpdateNegativeRHSValues(model);
foreach (Subject constarint in model.Subjects)
{
if (constarint.Equality != EquailtyType.LessEquals)
{
retval.Exception = new ArithmeticException();
retval.Message += "Constraint has Right-Hand Side Value " + constarint.RightHandValue.ToString() + " is " + constarint.Equality.ToString() + " different from " + EquailtyType.LessEquals.ToString() + "\n";
}
}
if (retval.Exception == null)
{
retval.Message = "Success";
}
return(retval);
}
public static void PrintMatrix(this ISimplexModel model)
{
string tmp_sign = string.Empty;
System.Diagnostics.Debug.WriteLine("*********************************");
System.Diagnostics.Debug.WriteLine(" Simplex Model");
System.Diagnostics.Debug.WriteLine("Goal :" + model.GoalType.ToString());
System.Diagnostics.Debug.Write("Objective Function - " + model.GoalType.ToString() + ": ");
foreach (Term item in model.ObjectiveFunction.Terms)
{
tmp_sign = string.Empty;
if (Math.Sign(item.Factor) > -1)
{
tmp_sign = "+";
}
System.Diagnostics.Debug.Write(tmp_sign + item.Factor + "*" + item.Vector + " ");
}
System.Diagnostics.Debug.WriteLine("");
int tmp_counter = 1;
foreach (Subject constaint in model.Subjects)
{
System.Diagnostics.Debug.Write("Constaint#" + tmp_counter + " :");
tmp_counter++;
foreach (Term item in constaint.Terms)
{
tmp_sign = string.Empty;
switch (Math.Sign(item.Factor))
{
case 1: tmp_sign = "+"; break;
case -1: tmp_sign = string.Empty; break;
default: tmp_sign = "+"; break;
}
System.Diagnostics.Debug.Write(tmp_sign + item.Factor + "*" + item.Vector + " ");
}
System.Diagnostics.Debug.Write(constaint.Equality.ToString() + " ");
System.Diagnostics.Debug.WriteLine(constaint.RightHandValue.ToString());
}
System.Diagnostics.Debug.WriteLine("*********************************");
}
public SimplexModelDecorator(ISimplexModel decoratedModel)
{
m_decoratedModel = decoratedModel;
m_testMessage = this.CheckBFS();
}
internal RevisedSimplexModel(ISimplexModel basemodel) : base(basemodel)
{
}
public static void ConvertStandardModel(this ISimplexModel model)
{
//Steps
//1.Modify the constraints so that the RHS of each constraint is nonnegative (This requires that each constraint with a negative RHS be multiplied by - 1.Remember that if you multiply an inequality by any negative number, the direction of the inequality is reversed!). After modification, identify each constraint as a ≤, ≥ or = constraint.
//2.Convert each inequality constraint to standard form(If constraint i is a ≤ constraint, we add a slack variable si; and if constraint i is a ≥ constraint, we subtract an excess variable ei).
//Two phase standardization
#region Phase I
//1) Check and update Right Hand Side- RHS value for positive
UpdateNegativeRHSValues(model);
//2) Add variables for BFS
//2.1) add slack,excess and artificial Term to constarints
string m_slackPrefix = "s";
int m_slackcount = 1;
string m_excessPrefix = "e";
int m_excesscount = 1;
string m_artificialPrefix = "a";
int m_artificialcount = 1;
foreach (Subject constarint in model.Subjects)
{
//1) add slack Term for not equal constarint
switch (constarint.Equality)
{
case EquailtyType.LessEquals: // if constarint equation <= then plus Slack variable at the left side
constarint.AddTerm(1, VariableType.Slack, m_slackPrefix + m_slackcount.ToString());
m_slackcount++;
break;
case EquailtyType.GreaterEquals: // if constarint equation >= then minus excess variable and plus artificial variable at the left side
constarint.AddTerm(-1, VariableType.Excess, m_excessPrefix + m_excesscount.ToString());
constarint.AddTerm(1, VariableType.Artificial, m_artificialPrefix + m_artificialcount.ToString());
m_excesscount++;
m_artificialcount++;
break;
default: // if constarint equation is eqal and subject dos nat contain basic term, then plus artificial variable at the left side
if (!constarint.Terms.Any(term => term.Basic == true))
{
constarint.AddTerm(1, VariableType.Artificial, m_artificialPrefix + m_artificialcount.ToString());
m_artificialcount++;
}
break;
}
}
//3) find the varibles in model and distinct them
Dictionary <string, TermCore> m_VectorList = new Dictionary <string, TermCore>();
//3.1) Check and collect vector label for objective funtion
foreach (Term term in model.ObjectiveFunction.Terms)
{
if (!m_VectorList.ContainsKey(term.Vector))
{
m_VectorList.Add(term.Vector, term.Core);
}
}
//3.2) //Check and collect vector label for constranit
foreach (Subject constarint in model.Subjects)
{
foreach (Term term in constarint.Terms)
{
if (!m_VectorList.ContainsKey(term.Vector))
{
m_VectorList.Add(term.Vector, term.Core);
}
}
}
//3) expand the objective function and all constarints with not exsit variable in Clause
//sort the vector list
foreach (KeyValuePair <string, TermCore> item in m_VectorList)
{
if (!model.ObjectiveFunction.IsVectorContained(item.Key))
{
model.ObjectiveFunction.Terms.Add(new Term()
{
Factor = 0, Core = item.Value
});
}
foreach (Subject constarint in model.Subjects)
{
if (!constarint.IsVectorContained(item.Key))
{
constarint.Terms.Add(new Term()
{
Factor = 0, Core = item.Value
});
}
}
}
//Sort clause terms
TermComparer tc = new TermComparer();
model.ObjectiveFunction.Terms.Sort(tc);
foreach (Subject constarint in model.Subjects)
{
constarint.Terms.Sort(tc);
}
//4) change signt the factor value of term in objective fonction terms and add positive balance variable ("Z")
foreach (Term term in model.ObjectiveFunction.Terms)
{
term.Factor *= -1;
}
model.ObjectiveFunction.RightHandValue = 0;
//find and flag basic variable
// if one of term that is non original contained only one cosntarint that ise basic varibale, let us find it
int tmp_zeroCounter = 0;
int tmp_OneCounter = 0;
int tmp_rowcount = model.Subjects.Count;
for (int i = 0; i < model.ObjectiveFunction.Terms.Count; i++)
{
tmp_zeroCounter = 0;
tmp_OneCounter = 0;
foreach (Subject constarint in model.Subjects)
{
if (constarint.Terms[i].Factor == 0)
{
tmp_zeroCounter++;
}
else if (constarint.Terms[i].Factor == 1)
{
tmp_OneCounter++;
}
}
if (tmp_OneCounter == 1 && (tmp_OneCounter + tmp_zeroCounter == tmp_rowcount))
{
model.ObjectiveFunction.Terms[i].Basic = true;
}
else
{
model.ObjectiveFunction.Terms[i].Basic = false;
}
}
////reflect basic flag from objective function to the cosntarint
//for (int i = 0; i < model.ObjectiveFunction.Terms.Count; i++)
//{
// foreach (Subject constarint in model.Subjects)
// {
// constarint.Terms[i].Basic= model.ObjectiveFunction.Terms[i].Basic;
// }
//}
//5) check the term count is equeal for objective function and all of constarints
#endregion
#region UnitMatrix
//List<Term> tmp_basicVariableslist = model.ObjectiveFunction.Terms.Where(item => item.isBasic).ToList();
//Dictionary<Term, int> tmp_UnitMatrixDictionary = new Dictionary<Term, int>();
//int tmp_index = -1;
//foreach (Term item in tmp_basicVariableslist)
//{
// tmp_index = -1;
// foreach (Subject constarint in model.Subjects)
// {
// tmp_index = constarint.Terms.FindIndex(consitem => consitem.Vector == item.Vector && consitem.Factor == 1);
// if (tmp_index > -1)
// {
// tmp_UnitMatrixDictionary.Add(item, tmp_index);
// break;
// }
// }
//}
#endregion
}
internal StandartSimplexModel(ISimplexModel basemodel) : base(basemodel)
{
}
