/// <summary>
/// Eliminate a row.
/// </summary>
/// <param name="pivot">The current pivot.</param>
private void Elimination(MatrixElement <Complex> pivot)
{
// Test for zero pivot
if (pivot.Value.Equals(0.0))
{
throw new SparseException("Matrix is singular");
}
pivot.Value = 1.0 / pivot.Value; // Inverse(pivot.Value);
var upper = pivot.Right;
while (upper != null)
{
// Calculate upper triangular element
// upper = upper / pivot
upper.Value *= pivot.Value;
var sub = upper.Below;
var lower = pivot.Below;
while (lower != null)
{
var row = lower.Row;
// Find element in row that lines up with the current lower triangular element
while (sub != null && sub.Row < row)
{
sub = sub.Below;
}
// Test to see if the desired element was not found, if not, create fill-in
if (sub == null || sub.Row > row)
{
sub = CreateFillin(row, upper.Column);
}
// element -= upper * lower
sub.Value -= upper.Value * lower.Value;
sub = sub.Below;
lower = lower.Below;
}
upper = upper.Right;
}
}
/// <summary>
/// Move a chosen pivot to the diagonal.
/// </summary>
/// <param name="pivot">The pivot element.</param>
/// <param name="step">The current step of factoring.</param>
public void MovePivot(MatrixElement <T> pivot, int step)
{
pivot.ThrowIfNull(nameof(pivot));
Strategy.MovePivot(Matrix, Rhs, pivot, step);
// Move the pivot in the matrix
var row = pivot.Row;
var column = pivot.Column;
if (row != step)
{
SwapRows(row, step);
}
if (column != step)
{
SwapColumns(column, step);
}
// Update the pivoting strategy
Strategy.Update(Matrix, pivot, step);
}
/// <summary>
/// Move a chosen pivot to the diagonal
/// </summary>
/// <param name="pivot">Pivot</param>
/// <param name="step">Step</param>
public void MovePivot(MatrixElement <T> pivot, int step)
{
if (pivot == null)
{
throw new ArgumentNullException(nameof(pivot));
}
Strategy.MovePivot(Matrix, Rhs, pivot, step);
// Move the pivot in the matrix
int row = pivot.Row;
int column = pivot.Column;
if (row != step)
{
SwapRows(row, step);
}
if (column != step)
{
SwapColumns(column, step);
}
Strategy.Update(Matrix, pivot, step);
}
