public int[] getFillPermutation()
{
return(applyReduce.getArrayP());
}
private bool performLU(DMatrixSparseCSC A)
{
int m = A.numRows;
int n = A.numCols;
int[] q = applyReduce.getArrayP();
// main loop for computing L and U
for (int k = 0; k < n; k++)
{
//--------- Triangular Solve
L.col_idx[k] = L.nz_length; // start of column k
U.col_idx[k] = U.nz_length;
// grow storage in L and U if needed
if (L.nz_length + n > L.nz_values.Length)
{
L.growMaxLength(2 * L.nz_values.Length + n, true);
}
if (U.nz_length + n > U.nz_values.Length)
{
U.growMaxLength(2 * U.nz_values.Length + n, true);
}
int col = q != null ? q[k] : k;
int top = TriangularSolver_DSCC.solve(L, true, A, col, x, pinv, gxi, gw);
int[] xi = gxi.data;
//--------- Find the Next Pivot. That will be the row with the largest value
//
int ipiv = -1;
double a = -double.MaxValue;
for (int p = top; p < n; p++)
{
int i = xi[p]; // x(i) is nonzero
if (pinv[i] < 0)
{
double t;
if ((t = Math.Abs(x[i])) > a)
{
a = t;
ipiv = i;
}
}
else
{
U.nz_rows[U.nz_length] = pinv[i];
U.nz_values[U.nz_length++] = x[i];
}
}
if (ipiv == -1 || a <= 0)
{
singular = true;
return(false);
}
// NOTE: The line is commented out below. It can cause a poor pivot to be selected. Instead of the largest
// row it will pick whatever is in this column. it does try to make sure it's not zero, but I'm not
// sure what it's purpose is.
// if( pinv[col] < 0 && Math.Abs(x[col]) >= a*tol ) {
// ipiv = col;
// }
//---------- Divide by the pivot
double pivot = x[ipiv];
U.nz_rows[U.nz_length] = k;
U.nz_values[U.nz_length++] = pivot; // last entry in U(:k) us U(k,k)
pinv[ipiv] = k;
L.nz_rows[L.nz_length] = ipiv; // First entry L(:,k) is L(k,k) = 1
L.nz_values[L.nz_length++] = 1;
for (int p = top; p < n; p++)
{
int i = xi[p];
if (pinv[i] < 0)
{
// x(i) is entry in L(:,k)
L.nz_rows[L.nz_length] = i;
L.nz_values[L.nz_length++] = x[i] / pivot;
}
x[i] = 0;
}
}
//----------- Finalize L and U
L.col_idx[n] = L.nz_length;
U.col_idx[n] = U.nz_length;
for (int p = 0; p < L.nz_length; p++)
{
L.nz_rows[p] = pinv[L.nz_rows[p]];
}
// Console.WriteLine(" reduce "+(reduceFill!=null));
// System.out.print(" pinv[ ");
// for (int i = 0; i < A.numCols; i++) {
// System.out.printf("%2d ",pinv[i]);
// }
// Console.WriteLine(" ]");
return(true);
}