# Module `Splittable_random`

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 `State.split`

operation for generating new pseudo-random states. While it is easy to simulate `State.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 `State.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.

`module State : sig ... end`

`val int : State.t -> lo:Base.int -> hi:Base.int -> Base.int`

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 int32 : State.t -> lo:Base.int32 -> hi:Base.int32 -> Base.int32`

`val int63 : State.t -> lo:Base.Int63.t -> hi:Base.Int63.t -> Base.Int63.t`

`val int64 : State.t -> lo:Base.int64 -> hi:Base.int64 -> Base.int64`

`val nativeint : State.t -> lo:Base.nativeint -> hi:Base.nativeint -> Base.nativeint`

`val float : State.t -> lo:Base.float -> hi:Base.float -> Base.float`

`val unit_float : State.t -> Base.float`

`unit_float state = float state ~lo:0. ~hi:1.`

, but slightly more efficient (and right endpoint is exclusive).

`module Log_uniform : sig ... end`