The vec operator of a matrix X consists of stacking columns of X one under another in a single vector. The vech operator of a square matrix X is obtained in the same way that vecX is defined, but it starts each column at its diagonal element. The objec-tive of this paper is to describe vec and vech operators and apply them to a multivariate mixed sire model.
FIRAT, M. Ziya (1998) "Application of vec and vech Operators to a Multivariate Mixed Sire Model," Turkish Journal of Veterinary & Animal Sciences: Vol. 22: No. 3, Article 12. Available at: https://journals.tubitak.gov.tr/veterinary/vol22/iss3/12