Wvec function

Vectorization operator that removes zeros

Wvec stacks columns of the given matrix to form a vector and removes elements that are zeros.

Wvec(W)

Arguments

• W: a size $(dxd)$ square matrix to be vectorized.

Returns

a vector of length $d^2 - n_zeros$ where $n_zeros$ is the number of zero entries in the matrix W.