Helper function for blow and hop moves
Gfun(case, npSel, pSel, h, x, x2)
Type of Twalk move. Either "hop" or "blow"
number of parameters that are changed.
vector containing information about which parameters are changed.
Parameter for "blow" and hop moves
parameter vector of chain 1
parameter vector of chain 2
Christen, J. Andres, and Colin Fox. "A general purpose sampling algorithm for continuous distributions (the t-walk)." Bayesian Analysis 5.2 (2010): 263-281.