sparskit::iludp Interface Reference

Computes the incomplete LU factorization of a sparse matrix in CSR format with standard dropping strategy. More...

Public Member Functions
subroutine	iludp (n, a, ja, ia, alph, droptol, permtol, mbloc, alu, jlu, ju, iwk, w, jw, iperm, ierr)

Detailed Description

Computes the incomplete LU factorization of a sparse matrix in CSR format with standard dropping strategy.

Parameters

[in]	n	The row dimension of the matrix.
[in]	a	The non-zero elements of matrix A.
[in]	ja	The column indices of matrix A.
[in]	ia	The index in A where the requested row starts.
[in]	alph	The diagonal compensation parameter. If ALPH = 0, the process is approximately equivalent to ILU with threshold; else, if ALPH = 1, the process is approximately equivalent to MILU with threshold.
[in]	droptol	The threshold for dropping small terms in the factorization.
[in]	permtol	A tolerance ratio used to determine whether or not to permute two columns. At step I, columns I and J are permuted when ABS(A(I,J)) * PERMTOL .GT. ABS(A(I,I)). Good values are typically between 0.1 to 0.01.
[in]	mbloc	If desired, permuting can be done only within the diagonal blocks of size MBLOC. Useful for PDE problems with many degrees of freedom. If this feature is not required, simply set MBLOC equal to N.
[out]	alu	The factored matrix stored in Modified Sparse Row (MSR) format containing the L and U factors together. The diagonal, stored in ALU(1:N), is inverted. Each i-th row of the ALU, JLU matrix contains the i-th row of L, excluding the diagonal entry, followed by the i-th row of U.
[out]	jlu	The column indices for the factored matrix.
[out]	ju	An N-element array containing the pointers to the beginning of each row of U in the factored matrix.
[in]	iwk	The lengths of alu and jlu.
[out]	w	An N+1 element workspace array.
[out]	jw	A 2*N element workspace array.
[out]	ierr	Error flag: 0: Successful return .gt. 0: Zero pivot encountered at step number IERR. -1: Input matrix is incorrect. The elimination process generated a row in L or U whose length is greater than N. -2: Insufficient storage for the LU factors. -3: Zero-valued row encountered.

Definition at line 499 of file sparskit.f90.

Constructor & Destructor Documentation

iludp()

subroutine sparskit::iludp::iludp	(	integer(int32), intent(in)	n,
		real(real64), dimension(*), intent(inout)	a,
		integer(int32), dimension(*), intent(inout)	ja,
		integer(int32), dimension(n+1), intent(inout)	ia,
		real(real64), intent(in)	alph,
		real(real64), intent(in)	droptol,
		real(real64), intent(in)	permtol,
		integer(int32), intent(in)	mbloc,
		real(real64), dimension(*), intent(out)	alu,
		integer(int32), dimension(*), intent(out)	jlu,
		integer(int32), dimension(n), intent(out)	ju,
		integer(int32), intent(in)	iwk,
		real(real64), dimension(2*n), intent(out)	w,
		integer(int32), dimension(2*n), intent(out)	jw,
		integer(int32), dimension(2*n), intent(out)	iperm,
		integer(int32), intent(out)	ierr )

Definition at line 499 of file sparskit.f90.

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The documentation for this interface was generated from the following file:

• D:/Code/linalg/src/sparskit.f90