Formula: f(beta, sigma2) proportional to sigma^-2 (eq. 6.2), flat in beta and in log(sigma). It is improper because it does not integrate to one, yet yields a proper posterior whenever X has full column rank. The density is returned up to its (infinite) normalizing constant.
References
Montesinos Lopez, Montesinos Lopez & Crossa (2022), Multivariate Statistical Machine Learning Methods for Genomic Prediction, Springer, eq. (6.2) p.172. DOI 10.1007/978-3-030-89010-0.
Examples
# the improper prior p(beta, sigma2) proportional to 1 / sigma2
Msm043(sigma2 = c(0.5))$density
#> [1] 2
