Which parameter triples to choose for xorshift family?

It seems almost all the implementations choose the (a,b,c) parameters arbitrarily. Some require input by the user. I'm wondering what our package should provide...

ref: http://www.jstatsoft.org/v08/i14/paper

Start by reading the referenced JSS paper and inspecting the package's existing xorshift implementations. Because the issue asks what the package should provide without defining a selection policy, confirm the intended parameter strategy with maintainers; done requires an agreed, concrete policy.

索引モデルが issue の本文から書いたものです。