Sfc64Engine Structure

Represents an SFC64 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 Sfc64Engine : IScalarEngine<ulong>, 
	IRandomEngine, IStateful

Visual Basic

Public Structure Sfc64Engine
	Implements IScalarEngine(Of ULong), IRandomEngine, 
	IStateful

C++/CLI

public value class Sfc64Engine : IScalarEngine<unsigned long long>, 
	IRandomEngine, IStateful

[<SealedAttribute>]
type Sfc64Engine = 
    struct
        inherit ValueType
        interface IScalarEngine<uint64>
        interface IRandomEngine
        interface IStateful
    end

Inheritance: Object → ValueType → Sfc64Engine

Implements: IRandomEngine, IScalarEngine<UInt64>, IStateful

Remarks

The SFC64 (Small Fast Chaotic 64-bit) engine is a chaotic pseudo-random number generator by Chris Doty-Humphrey. It uses simple operations (addition, rotation, and XOR) to achieve excellent speed and statistical properties.

Algorithm Details:

State size: 256 bits (3 × 64-bit words + 1 counter)
Output function: Chaotic mixing with three-rotate operations
Period: Minimum 2⁶⁴, average approximately 2²⁵⁵
Performance: Very fast with excellent statistical quality

Statistical Quality:

SFC64 passes all statistical tests including BigCrush and PractRand with no failures. It uses only simple operations making it highly efficient on modern processors.

Use Cases:

Ideal for high-performance computing, simulations, games, and Monte Carlo methods where speed and quality are both critical. The chaotic mixing provides strong decorrelation between outputs.

Advancement:

SFC64 does not support mathematical advancement or jumping due to its chaotic nature. Only implements IStateful for state persistence.

Reference: Chris Doty-Humphrey. "PractRand: Practical PRNG Testing." http://pracrand.sourceforge.net/

Example

var engine = new Sfc64Engine();
engine.Seed(SeedSequences.SplitMix64(123));

ulong value = engine.Next();

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

Properties

BitsPerWord	Gets the native word size in bits.
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.
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)
LoadState	Loads the engine's state from the source span in a stable little-endian format.
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, UInt64, UInt64)	Directly sets the SFC64 state words and counter.
ToString	Returns the fully qualified type name of this instance. (Inherited from ValueType)