private void SwapRows(Equation equation, ref bool[] hasZeroRows, Pivot pivot)
{
for (int i = 0; i < equation.RowsCount; i++)
{
(equation.Coefficients[pivot.Row, i], equation.Coefficients[pivot.Column, i]) =
(equation.Coefficients[pivot.Column, i], equation.Coefficients[pivot.Row, i]);
}
(equation.Intercepts[pivot.Row], equation.Intercepts[pivot.Column]) =
(equation.Intercepts[pivot.Column], equation.Intercepts[pivot.Row]);
(hasZeroRows[pivot.Row], hasZeroRows[pivot.Column]) = (hasZeroRows[pivot.Column], hasZeroRows[pivot.Row]);
pivot.Row = pivot.Column;
}
private double[] RowReduction(Equation equation)
{
bool[] hasZeroRows = new bool[equation.RowsCount];
bool[] hasZeroCols = new bool[equation.RowsCount];
//convert the matrix into an upper triangular matrix
for (int i = 0; i < equation.RowsCount; i++)
{
Pivot pivot = SelectPivot(equation, hasZeroRows, hasZeroCols);
SwapRows(equation, ref hasZeroRows, pivot);
ForwardElimination(equation, pivot, ref hasZeroRows, ref hasZeroCols);
}
//reduction to row echelon form
BackSubstitution(equation);
return(equation.Intercepts);
}
private void RowReduction(double[] row, Equation equation)
{
while (true)
{
Pivot pivot = SelectPivot(row, equation);
if (pivot.Row == -1 || pivot.Column == -1 || CurrentSolution == Solution.Infinity)
{
break;
}
ResultVariables[pivot.Column] = pivot.Row;
double divisor = equation.Coefficients[pivot.Row, pivot.Column];
equation.Intercepts[pivot.Row] /= divisor;
for (int i = 0; i < equation.ColsCount; i++)
{
equation.Coefficients[pivot.Row, i] /= divisor;
}
double multiple = 0;
for (int i = 0; i < equation.RowsCount; i++)
{
if (pivot.Row != i && !EqualToZero(equation.Coefficients[i, pivot.Column]))
{
multiple = equation.Coefficients[i, pivot.Column];
equation.Intercepts[i] -= equation.Intercepts[pivot.Row] * multiple;
for (int j = 0; j < equation.ColsCount; j++)
{
equation.Coefficients[i, j] -=
equation.Coefficients[pivot.Row, j] * multiple;
}
}
}
int size = equation.Intercepts.Length;
if (CurrentPhase == Phase.One)
{
equation.Intercepts[size - 2] -=
equation.Intercepts[pivot.Row] * equation.Function[pivot.Column];
equation.Intercepts[size - 1] -=
equation.Intercepts[pivot.Row] * row[pivot.Column];
double functionCol = equation.Function[pivot.Column];
double rowCol = row[pivot.Column];
for (int i = 0; i < equation.ColsCount; i++)
{
equation.Function[i] -=
equation.Coefficients[pivot.Row, i] * functionCol;
row[i] -=
equation.Coefficients[pivot.Row, i] * rowCol;
}
SecondaryRow = row;
}
else
{
equation.Intercepts[size - 1] -=
equation.Intercepts[pivot.Row] * equation.Function[pivot.Column];
multiple = equation.Function[pivot.Column];
for (int i = 0; i < equation.ColsCount; i++)
{
equation.Function[i] -=
equation.Coefficients[pivot.Row, i] * multiple;
}
equation.Function = row;
}
}
}
