On Sun, May 24, 2015 at 7:56 PM, Sturla Molden <sturla.molden@gmail.com> wrote:
>
> On 24/05/15 20:04, Nathaniel Smith wrote:
>
> > I'm not sure what you're envisioning as needing a deprecation cycle? The
> > neat thing about random is that we already have a way for users to say
> > that they want replicability -- the use of an explicit seed --
>
> No, this is not sufficient for random numbers. Random sampling and
> ziggurat generators are examples. If we introduce a change (e.g. a
> bugfix) that will affect the number of calls to the entropy source, just
> setting the seed will in general not be enough to ensure backwards
> compatibility. That is e.g. the case with using ziggurat samplers
> instead of the current transcendental transforms for normal, exponential
> and gamma distributions. While ziggurat is faster (and to my knowledge)
> more accurate, it will also make a different number of calls to the
> entropy source, and hence the whole sequence will be affected, even if
> you do set a random seed.

Please reread the proposal at the top of the thread.

--
Robert Kern