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. Sturla