phi1 function returns NA or Inf for large values of x

[merliseclyde]

Describe the bug
For large values of the Wald statistic (typical with large n) the current implementation of the Phi1 function in BAS returns NA or Inf
due to overflow in the exponential function. This impacts Bayes factor calculations with several prior distributions
in bas.glm, such as the hyper-g/n

To Reproduce
Steps to reproduce the behavior:

BAS::phi1(1, 2, 1.5, 1000, 1/100)

Reported by Daniel Heeman

[merliseclyde]

Fixed as of BS 1.6.2

Note

BAS::phi1(1, 2, 1.5, 1000, 1/100, log=FALSE)

still returns Inf

Use

BAS::phi1(1, 2, 1.5, 1000, 1/100, log=TRUE)

as the result is greater that the largest double for exponentiating