Multivariate Probabilities of Scale Mixtures of Multivariate
Normal Distributions via the Genz and Bretz (2002) QRSVN Method
Generates multivariate subgaussian stable probabilities using the QRSVN
algorithm as detailed in Genz and Bretz (2002)
but by sampling positive stable variates not chi/sqrt(nu).
mvgb
Multivariate probabilities via the Genz and Bretz method