ckron_indices()

static CubicOperator.ckron_indices(r)

Construct a mask for efficiently computing the compressed Kronecker triple product.

This method provides a faster way to evaluate ckron() when the state dimension r is known a priori.

Parameters

rint

State dimension.

Returns

maskndarray

Compressed Kronecker product mask.

Examples

>>> from opinf.operators import CubicOperator
>>> r = 20
>>> mask = CubicOperator.kron_indices(r)
>>> q = np.random.random(r)
>>> np.allclose(CubicOperator.ckron(q), np.prod(q[mask], axis=1))
True