Xoroshiro128PlusPlusEngine Structure

Represents a Xoroshiro128++ random number generator engine with 64-bit output.

Definition

Namespace: Numerics.NET.Random.Engines
Assembly: Numerics.NET (in Numerics.NET.dll) Version: 10.3.0

public struct Xoroshiro128PlusPlusEngine : IScalarEngine<ulong>, 
	IRandomEngine, IStateful, IAdvanceable, IJumpable

Visual Basic

Public Structure Xoroshiro128PlusPlusEngine
	Implements IScalarEngine(Of ULong), IRandomEngine, 
	IStateful, IAdvanceable, IJumpable

C++/CLI

public value class Xoroshiro128PlusPlusEngine : IScalarEngine<unsigned long long>, 
	IRandomEngine, IStateful, IAdvanceable, IJumpable

[<SealedAttribute>]
type Xoroshiro128PlusPlusEngine = 
    struct
        inherit ValueType
        interface IScalarEngine<uint64>
        interface IRandomEngine
        interface IStateful
        interface IAdvanceable
        interface IJumpable
    end

Inheritance: Object → ValueType → Xoroshiro128PlusPlusEngine

Implements: IRandomEngine, IScalarEngine<UInt64>, IAdvanceable, IJumpable, IStateful

Remarks

The Xoroshiro128++ (Xor-Rotate-Shift-Rotate 128 Plus-Plus) engine is a 64-bit random number generator by David Blackman and Sebastiano Vigna. It features a 128-bit state with a period of 2¹²⁸ - 1 and passes all statistical tests.

Algorithm Details:

State size: 128 bits (2 × 64-bit words)
Output function: ++ (Plus-Plus) scrambler: rotl(s[0] + s[1], 17) + s[0]
Period: 2¹²⁸ - 1
Performance: Excellent speed with smaller state

Compatibility:

This is faster than the xoshiro256 family but with a smaller state space, making it ideal for applications that need speed but don't require the longest period.

Use Cases:

The "++" scrambler provides excellent statistical quality suitable for all purposes except for generating more than 2⁶⁴ random numbers without jumping.

Reference: David Blackman and Sebastiano Vigna. "Scrambled Linear Pseudorandom Number Generators." ACM Trans. Math. Softw. 2021.

Example

var engine = new Xoroshiro128PlusPlusEngine();
engine.Seed(SeedSequences.SplitMix64(123));

ulong value = engine.Next();

ulong[] values = new ulong[100];
engine.Fill(values);

// Jump for parallel streams
engine.Jump();

Properties

BitsPerWord	Gets the native word size in bits.
JumpSize	Gets the size category of the primary jump operation.
LongJumpSize	Gets the size category of the long jump operation.
Name	Gets a human-readable name for this engine.
StateSize	Gets the number of bytes required to save/load this engine's state.

Methods

Advance()	Advances the engine state by one transition step.
Advance(UInt64)	Advances the RNG state by the specified number of outputs.
Equals	Indicates whether this instance and a specified object are equal. (Inherited from ValueType)
Fill	Fills the destination span with successive native words from the engine's stream.
GetHashCode	Returns the hash code for this instance. (Inherited from ValueType)
GetType	Gets the Type of the current instance. (Inherited from Object)
Jump	Jumps the RNG forward by the specified number of primary jump strides.
LoadState	Loads the engine's state from the source span in a stable little-endian format.
LongJump	Jumps the RNG forward by the specified number of long jump strides.
Next	Advances the engine by one step and returns the native word produced for that step.
Output	Returns the native word produced by applying the output mapping function to the current engine state, without mutating that state.
SaveState	Saves the engine's state to the destination span in a stable little-endian format.
Seed(SeedSequence)	Initializes the engine state from a seed sequence.
Seed(UInt64, UInt64)	Directly sets the two 64-bit state words.
ToString	Returns the fully qualified type name of this instance. (Inherited from ValueType)