Module Splittable_randomSource
A splittable pseudo-random number generator (SPRNG) functions like a PRNG in that it can be used as a stream of random values; it can also be "split" to produce a second, independent stream of random values.
This module implements a splittable pseudo-random number generator that sacrifices cryptographic-quality randomness in favor of performance.
The primary difference between Splittable_random and Random is the split operation for generating new pseudo-random states. While it is easy to simulate split using Random, the result has undesirable statistical properties; the new state does not behave independently of the original. It is better to switch to Splittable_random if you need an operation like split, as this module has been implemented with the statistical properties of splitting in mind. For most other purposes, Random is likely a better choice, as its implementation passes all Diehard tests, while Splittable_random fails some Diehard tests.
Create a new t seeded from the given random state. This allows nondeterministic initialization, for example in the case that the input state was created using Random.make_self_init.
Constructors like create and of_int should be called once at the start of a randomized computation and the resulting state should be threaded through. Repeatedly creating splittable random states from seeds in the middle of computation can defeat the SPRNG's splittable properties.
Create a new t that will return identical results to any other t created with that integer.
perturb t salt adds the entropy of salt to t.
Create a copy of t that will return the same random samples as t.
val copy_into_capsule :
Splittable_random.t @ shared ->
(Splittable_random.t, 'k) Capsule_expert.Data.t @@ portableLike copy, but puts the result in an arbitrary capsule.
split t produces a new state that behaves deterministically (i.e. only depending on the state of t), but pseudo-independently from t. This operation mutates t, i.e., t will return different values than if this hadn't been called.
val split_into_capsule :
Splittable_random.t ->
(Splittable_random.t, 'k) Capsule_expert.Data.t @@ portableLike split, but puts the result into an arbitrary capsule.
Produces a random, fair boolean.
Produce a random number uniformly distributed in the given inclusive range. (In the case of float, hi may or may not be attainable, depending on rounding.)
val int63 :
Splittable_random.t ->
lo:Base.Int63.t ->
hi:Base.Int63.t ->
Base.Int63.t @@ portableval nativeint :
Splittable_random.t ->
lo:Base.nativeint ->
hi:Base.nativeint ->
Base.nativeint @@ portableunit_float state = float state ~lo:0. ~hi:1., but slightly more efficient (and right endpoint is exclusive).