This function fist a probabilistic linear regression model with variational Bayesian inference. For the ordinary regularized linear regression, user has to manually assign the regularization parameter. However, Variational Bayesian method can do model selection automatically, that is it can automatically determine proper parameter from the data.
This package is now a part of the PRML Toolbox (http://www.mathworks.com/matlabcentral/fileexchange/55826-pattern-recognition-and-machine-learning-toolbox).