cov2vec: Transform a variance matrix into a vector
Description
Transform a variance matrix into a vector i.e., Sigma=R^T*R
Usage
cov2vec(sigma)
Value
par A vector representing a variance matrix
Arguments
sigma
A \(p\times p\) variance matrix
Details
The variance matrix is decomposed by computing the Choleski factorization of a real symmetric positive-definite square matrix.
Then, storing the upper triangular factor of the Choleski decomposition into a vector.