scipy.linalg.lapack.cpstrf

scipy.linalg.lapack.cpstrf(a, tol=-1.0, lower=0, overwrite_a=0) = <flapack function cpstrf>

Compute the pivoted Cholesky factorization of a positive semidefinite matrix, blocked (LAPACK cpstrf).

Parameters:

andarray

Symmetric or Hermitian positive semidefinite matrix of shape (n, n).

tolfloat, optional

Pivots at or below this value stop the factorization. Default is -1.0, which uses n * eps * max(diag(a)).

lowerint, optional

If nonzero, the lower triangle of a is referenced and the factor is lower triangular; otherwise the upper. Default is 0.

overwrite_aint, optional

If nonzero, a may be overwritten in place. Default is 0.

Returns:

cndarray

The factor, in the selected triangle, of p.T @ a @ p. The opposite triangle is left as it was in a.

pivndarray

Pivot indices, 1-based: column i of p is column piv[i] - 1 of the identity. Unlike getrf, this family does not shift them down.

rank_cint

Computed rank of a, as determined by tol.

infoint

0 on success; if negative, the -info-th argument had an illegal value; if 1, a is not positive definite but the rank-deficient factorization completed.