private bool HavePositiveCellsWithoutPositiveElements(SimplexTable table)
{
for (var j = 0; j < table.Variables.Count; j++)
{
if (table.GetRating(table.Variables.ElementAt(j)) <= 0) continue;
var havePositive = false;
for (var i = 0; i < table.RowsCount; i++)
{
if (table.GetMatrixElement(i, j) < 0) continue;
havePositive = true;
break;
}
if (!havePositive) return true;
}
return false;
}
/// <summary>
/// Returns index of solving cell(or -1 if table has no positive rating)
/// </summary>
/// <param name="table">Table with calculated ratings</param>
/// <param name="solvingRowIndex">Index of solving row</param>
private int GetSolvingCellIndex(SimplexTable table, int solvingRowIndex)
{
if (solvingRowIndex < 0) return -1;
var minRatioIndex = -1;
var minRatio = new MaxCoefficient();
for (var i = 0; i < table.Variables.Count; i++)
{
var matrixElement = table.GetMatrixElement(solvingRowIndex, i);
if (matrixElement >= 0) continue;
var rating = table.Ratings[i];
var currRatio = new MaxCoefficient(rating);
currRatio.Multiply(1 / matrixElement);
if (currRatio.CompareTo(minRatio) != -1 && minRatioIndex != -1) continue;
minRatioIndex = i;
minRatio = currRatio;
}
return minRatioIndex;
}
/// <summary>
/// Returns index of solving row(or -1 if solving row has no positive elements or solvingCellIndex == -1)
/// </summary>
private int GetSolvingRowIndex(SimplexTable table, int solvingCellIndex)
{
if (solvingCellIndex < 0) return -1;
var minRatioIndex = -1;
var minRatio = new Fraction();
for (var i = 0; i < table.RowsCount; i++)
{
var matrixElement = table.GetMatrixElement(i, solvingCellIndex);
if (matrixElement <= 0) continue;
var freeCoefficient = table.GetFreeCoefficient(i);
var currRatio = freeCoefficient / matrixElement;
if (currRatio >= minRatio && minRatioIndex != -1) continue;
minRatioIndex = i;
minRatio = currRatio;
}
return minRatioIndex;
}
/// <summary>
/// Gets result of solving of normalized problem
/// </summary>
public LppResult GetNormalizedProblemResult(SimplexTable table)
{
for (var i = 0; i < table.Variables.Count; i++)
{
if (table.GetRating(table.Variables.ElementAt(i)) <= 0) continue;
var allNegative = true;
for (var j = 0; j < table.RowsCount; j++)
{
if (table.GetMatrixElement(j, i) >= 0)
allNegative = false;
}
if (allNegative)
return new LppResult(null, null);
}
return GetResult(table, VariablesWithMaxCoefficient);
}
