scipy.linalg.lapack.dtrexc

scipy.linalg.lapack.dtrexc(a, q, ifst, ilst, wantq=1, overwrite_a=0, overwrite_q=0) = <flapack function dtrexc>

Reorder a Schur decomposition by moving one diagonal block (LAPACK dtrexc).

Parameters:

andarray

Upper (quasi-)triangular Schur form of shape (n, n).

qndarray

Matrix of Schur vectors; updated when wantq is nonzero.

ifstint

Current position of the diagonal block to move, 1-based.

ilstint

Position to move it to, 1-based. LAPACK adjusts both when a block turns out to be 2x2; the adjusted values are not returned.

wantqint, optional

If nonzero, the transformation is accumulated into q. Default is 1.

overwrite_aint, optional

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

overwrite_qint, optional

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

Returns:

andarray

The reordered Schur form.

qndarray

The updated Schur vectors.

infoint

0 on success; if negative, the -info-th argument had an illegal value.