[R] new dgamma rate argument

[Jim Lindsey]

> 
> >>>>> "Jim" == Jim Lindsey <james.lindsey at luc.ac.be> writes:
> 
>     Jim> Can someone explain to me in what way the new
>     Jim> (dpqr)gamma parameter can be interpreted as a rate
>     Jim> (when shape != 1)? The only gamma rate that I am aware
>     Jim> of is the hazard rate given by dgamma/(1-pgamma), the
>     Jim> log of which is returned by my hgamma function (event
>     Jim> library).  Jim
> 
> NEWS has
> 
>     o	[dpqr]gamma now has third argument `rate' for S-compatibility
> 	(and for compatibility with exponentials).  Calls which use
> 	positional matching may need to be altered.
> 
> i.e. one point of view (close to mine) could be:
> 
>  The authors of R (R&R) called that argument of [dpqr]gamma()
>  `scale' as it should sensibly be called.
>  OTOH, (at least one of) the original S authors used `rate'
>  (for 1/scale) in a loose analogy with the exponential and
>  weibull distribution quite some time before R was born.  Now
>  that there is an increasing drive for S source compatibility
>  between the different S dialects --  whenever it's ``easy'' --
>  the compatible parametrization has been allowed as well.

That does not answer my question. Of course, I read the NEWS but a
misleading error in one system is not a reason for copying it into R.
There is no rate parameter in the Weibull either, only
dweibull/(1-pweibull) as well. Only the exponential has a constant
rate.
  Jim

> 
> Martin
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