`scipy.linalg._flapack:cuncsd`

source: build-install/usr/lib/python3.14/site-packages/scipy/linalg/_flapack.cpython-314-x86_64-linux-gnu.so

Signature

def cuncsd(x11, x12, x21, x22, compute_u1 = 1, compute_u2 = 1, compute_v1t = 1, compute_v2t = 1, trans = 0, signs = 0, lwork = Ellipsis, lrwork = Ellipsis, overwrite_x11 = 0, overwrite_x12 = 0, overwrite_x21 = 0, overwrite_x22 = 0)

Summary

CS decomposition of a partitioned unitary matrix (LAPACK cuncsd).

Extended Summary

The matrix arrives as its four blocks and comes back transformed, alongside the angles theta and the four factors.

Parameters

x11 : ndarray: Leading block, shape (p, q); it sets p and q.
x12 : ndarray: Upper right block, shape (p, m - q).
x21 : ndarray: Lower left block, shape (m - p, q).
x22 : ndarray: Trailing block, shape (m - p, m - q); with x11 it sets m.
compute_u1 : int, optional: If nonzero, u1 is computed. Default is 1.
compute_u2 : int, optional: If nonzero, u2 is computed. Default is 1.
compute_v1t : int, optional: If nonzero, v1t is computed. Default is 1.
compute_v2t : int, optional: If nonzero, v2t is computed. Default is 1.
trans : int, optional: If nonzero, the blocks are read row-major rather than column-major. Default is 0.
signs : int, optional: If nonzero, the alternate sign convention is used. Default is 0.
lwork : int, optional: Workspace size; -1 requests the query. Query it with cuncsd_lwork.
lrwork : int, optional: Real workspace size; -1 requests the query. The real flavors have no second workspace and take no lrwork.
overwrite_x11, overwrite_x12, overwrite_x21, overwrite_x22 : int, optional: If nonzero, the matching block may be overwritten in place. Default is 0.

Returns

cs11, cs12, cs21, cs22 : ndarray: The transformed blocks.
theta : ndarray: The CS angles, length min(p, m - p, q, m - q). Real for every flavor.
u1, u2, v1t, v2t : ndarray: The factors, each empty unless its compute_* flag was set.
info : int: 0 on success; if negative, the -info-th argument had an illegal value.

Aliases

scipy.linalg._flapack.cuncsd