public LinearProgram Solve()
{
bool solved = false;
ProblemNode currentOptimal = problems.ElementAt(0);
//loop runs until all problems are solved, exit via break
while (true)
{
ProblemNode currentProblem = (ProblemNode)problems.ElementAt(0);
//this loop checks to see if all problems are solved
for (int i = 0; i < problems.Count; i++)
{
if (!problems.ElementAt(i).Solved)
{
currentProblem = problems.ElementAt(i);
break;
}
if (problems.Count == i + 1)
{
solved = true;
}
}
if (solved)
{
break;
}
if (LpTools.IsSpecialCase(currentProblem.Problem))
{
currentProblem.Solved = true;
continue;
}
Dual dual = new Dual(currentProblem.Problem);
currentProblem.Problem = dual.Solve();
currentProblem.ZValue =
currentProblem.Problem.LinearProgramMatrix[0, currentProblem.Problem.ColumnCount - 1];
currentProblem.Solved = true;
//double[] xValues = new double[currentProblem.Problem.CountX];
double[] xValues = LpTools.findXValues(currentProblem.Problem);
//for (int i = 0; i < xValues.Length; i++)
// xValues[i] = Math.Round(currentProblem.Problem.LinearProgramMatrix[i+1, currentProblem.Problem.ColumnCount-1],5);
currentProblem.XValues = xValues;
Console.WriteLine("\n\nAdding Constraints:");
Console.WriteLine("===================================================================");
for (int i = 0; i < xValues.Length; i++)
{
if ((xValues[i] % 1) != 0)
{
problems.Add(new ProblemNode(
LpTools.AddBasicConstraint(currentProblem.Problem, i + 1, LpTools.LESS_THAN, (int)xValues[i]),
false, null, 0));
Console.WriteLine("\n");
problems.Add(new ProblemNode(
LpTools.AddBasicConstraint(currentProblem.Problem, i + 1, LpTools.GREATER_THAN, (int)xValues[i] + 1),
false, null, 0));
}
}
Console.WriteLine("===================================================================");
//todo: check for infinte loop when initial problem cannot be solved
if ((type == LPType.Max && currentProblem.ZValue > currentOptimal.ZValue) ||
(type == LPType.Min && currentOptimal.ZValue > currentProblem.ZValue) ||
currentOptimal.XValues.Any((x) => x % 1 != 0))
{
currentOptimal = currentProblem;
}
}
return(currentOptimal.Problem);
}
//Loop this?
public static void SensitivityAnalysisMenu()
{
try
{
//Sensitivity Analysis Menu
Console.WriteLine(@"
IP SOLVER
________________________________________________________________________________________
SENSITIVITY ANALYSIS
1. Display the range of a selected Non-Basic Variable.
2. Apply and display a change of a selected Non-Basic Variable.
3. Display the range of a selected Basic Variable.
4. Apply and display a change of a selected Basic Variable.
5. Display the range of a selected constraint right-hand-side value.
6. Apply and display a change of a selected constraint right-hand-side value.
7. Display the range of a selected variable in a Non-Basic Variable column.
8. Apply and display a change of a selected variable in a Non-Basic Variable column.
9. Add a new activity to an optimal solution.
10. Add a new constraint to an optimal solution.
11. Display the shadow prices.
12. Duality
");
Console.WriteLine("\nSolved LP\n");
linearProgram.DisplayCurrentTable();
Console.WriteLine();
int userInputSensitivityAnalysis = int.Parse(Console.ReadLine());
SensitivityMenu smenu = (SensitivityMenu)userInputSensitivityAnalysis;
switch (smenu)
{
case SensitivityMenu.display1:
//TODO Display the range of a selected Non-Basic Variable.
//SensivitityAnalysis.GetNonBasicVariables(linearProgram);
Console.WriteLine("Enter the column Number: (Z Column = Column 0)");
int rowNumber = int.Parse(Console.ReadLine());
Console.WriteLine("Ranges for Non Basic Variables");
SensivitityAnalysis.GetNBVRange(SensivitityAnalysis.GetFormatedSensistivityMatrix(linearProgram.LinearProgramMatrix), rowNumber);
Console.ReadKey();
break;
case SensitivityMenu.display2:
//TODO Display the range of a selected Non-Basic Variable.
Console.WriteLine("Enter the column Number: (Z Column = Column 0)");
int columnNumber = int.Parse(Console.ReadLine());
Console.WriteLine("Enter the row Number: (Z Column = Column 0)");
rowNumber = int.Parse(Console.ReadLine());
if (linearProgram.GetBasicVariables()[columnNumber] != 0)
{
Console.WriteLine("Not NBV");
}
else
{
Console.WriteLine("ENter NEw Value:");
int valuenew = int.Parse(Console.ReadLine());
linearProgram.LinearProgramMatrix[rowNumber, columnNumber] = valuenew;
linearProgram.DisplayCurrentTable();
if (LpTools.CheckIfIPIsSolved(linearProgram))
{
Console.WriteLine("No Change");
Console.ReadKey();
}
else
{
LinearProgram linearProgramNew = (LinearProgram)linearProgram.Clone();
Dual dual2 = new Dual(linearProgramNew);
dual2.Solve();
if (LpTools.CheckIfIPIsSolved(linearProgramNew))
{
linearProgramNew.DisplaySolution();
}
else
{
Console.WriteLine("No solution");
Console.ReadKey();
}
}
}
break;
case SensitivityMenu.display3:
//TODO Display the range of a selected Basic Variable.
Console.WriteLine("Enter the column Number: (Z Column = Column 0)");
rowNumber = int.Parse(Console.ReadLine());
Console.WriteLine("Ranges for Basic variables");
SensivitityAnalysis.GetRangesForSelectedBV(SensivitityAnalysis.GetFormatedSensistivityMatrix(linearProgram.LinearProgramMatrix), rowNumber);
Console.ReadKey();
break;
case SensitivityMenu.display4:
//TODO Apply and display a change of a selected Basic Variable.
break;
case SensitivityMenu.display5:
//TODO Display the range of a selected constraint right-hand-side value.
//Console.WriteLine("Enter the row Number: (Z Row = Row 0)");
//rowNumber = int.Parse(Console.ReadLine());
Console.WriteLine("Ranges for RHS variables");
SensivitityAnalysis.GetRangesForRHS(SensivitityAnalysis.GetFormatedSensistivityMatrix(linearProgram.LinearProgramMatrix), linearProgram);
Console.ReadKey();
break;
case SensitivityMenu.display6:
//TODO Apply and display a change of a selected constraint right-hand-side value.
break;
case SensitivityMenu.display7:
//TODO Display the range of a selected variable in a Non-Basic Variable column.
break;
case SensitivityMenu.display8:
//TODO Apply and display a change of a selected variable in a Non-Basic Variable column.
Console.WriteLine("Under Construction");
Console.ReadKey();
break;
case SensitivityMenu.display9:
//TODO Add a new activity to an optimal solution.
break;
case SensitivityMenu.display10:
//TODO Add a new constraint to an optimal solution.
Console.WriteLine("Enter the X Number: (Z Row = Row 0)");
rowNumber = int.Parse(Console.ReadLine());
Console.WriteLine("Type:\n1. <= \n2 . >=");
int sign = int.Parse(Console.ReadLine());
Console.WriteLine("RHS:");
int rhs = int.Parse(Console.ReadLine());
linearProgram = LpTools.AddBasicConstraint(linearProgram, rowNumber, sign - 1, rhs);
Console.WriteLine("New Table");
linearProgram.DisplayCurrentTable();
LinearProgram newLP = (LinearProgram)linearProgram.Clone();
Dual dual = new Dual(newLP);
dual.Solve();
if (LpTools.CheckIfIPIsSolved(newLP))
{
linearProgram.DisplaySolution();
}
else
{
Console.WriteLine("No solution");
Console.ReadKey();
}
break;
case SensitivityMenu.display11:
//TODO Display the shadow prices.
Console.WriteLine("shadow prices.");
SensivitityAnalysis.GetShadowPrices(SensivitityAnalysis.GetFormatedSensistivityMatrix(linearProgram.LinearProgramMatrix), linearProgram);
Console.ReadKey();
break;
case SensitivityMenu.display12:
//TODO Duality
Duality duality = new Duality(linearProgram);
duality.DeterminDuality();
Console.ReadKey();
break;
default:
break;
}
}
catch (FormatException)
{
Console.WriteLine("Invalid Input");
}
}
