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_ldl_construct_tri_factor(lu, swap_vec, pivs, lower=True)

If lower is True the permuted factors are multiplied as L(1)*L(2)*...*L(k). Otherwise, the permuted factors are multiplied as L(k)*...*L(2)*L(1). See LAPACK documentation for more details.

Notes

Note that the original argument "lu" is overwritten.

Parameters

lu : ndarray

The triangular array that is extracted from LAPACK routine call with ones on the diagonals.

swap_vec : ndarray

The array that defines the row swapping indices. If the kth entry is m then rows k,m are swapped. Notice that the mth entry is not necessarily k to avoid undoing the swapping.

pivs : ndarray

The array that defines the block diagonal structure returned by _ldl_sanitize_ipiv().

lower : bool, optional

The boolean to switch between lower and upper triangular structure.

Returns

lu : ndarray

The square outer factor which satisfies the L * D * L.T = A

perm : ndarray

The permutation vector that brings the lu to the triangular form

Helper function to construct explicit outer factors of LDL factorization.

Examples

See :

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GitHub : /scipy/linalg/_decomp_ldl.py#298
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