resymbol¶

CholeskyFactor.resymbol(A, is_permuted=True)[source]¶

Recompute the symbolic Cholesky factorization of a sparse matrix.

This function is useful after a series of downdates via update() or rowdel(), since downdates do not remove any entries in L [1].

Parameters:

A ((N, N) csc_array) – The input matrix in Compressed Sparse Column (CSC) format. Must be square and symmetric. Only the lower triangular part of A is used, and no check is made for symmetry. The numerical values of A are ignored. Only its non-zero pattern is used.

Note

The input matrix A is expected to be the permuted matrix \(P A P^{\top}\), where P is the permutation matrix corresponding to the permutation vector returned by get_perm().
is_permuted (bool) – If True (default), the input matrix A is assumed to be permuted by the fill-reducing permutation used in the factorization: \(P A P^{\top}\). If False, A is assumed to be in the original ordering.

Returns:

CholeskyFactor – The current object, for method chaining.