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MWC64X

MWC64X is a GPU-optimized 64-bit Multiply-With-Carry generator designed for OpenCL/CUDA with period ~2^63. It uses minimal state (64 bits) and very fast operations (5-6 instructions) while passing rigorous statistical tests. Ideal for massively parallel simulations.

Properties

Property	Value
Category	Random Number Generators
Sub-category	Multiply-With-Carry PRNG
Security status	🎓 Educational Only
Complexity	Intermediate
Inventor	David B. Thomas
Year	2011
Origin	🇬🇧 United Kingdom
Source	algorithms/random/mwc64x.js

Parameters

Parameter	Supported values
Seed sizes	1 byte (8 bits) to 8 bytes (64 bits)

Capabilities

Flag	Value
IsDeterministic	Yes
IsCryptographicallySecure	No

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• Official MWC64X Page (David B. Thomas, Imperial College)
• Original MWC Paper: Marsaglia&Zaman (1991)
• OpenCL Implementation Example (GitHub)
• SYCL-PRNG Library (MWC64X implementation)

References

• GPU Random Number Generation Review
• Wikipedia: Multiply-with-carry pseudorandom number generator

Test vectors

5 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — Seed 1: First 10 outputs (40 bytes) - x=1, c=0

Field	Value
seed	0100000000000000
outputSize	40
input	null
expected	010000001bb8feffeea2075ccba5b14e a56f21525d2fe55ccf64d299cf405917 8eeb1d4329577ced

Vector 2 — Seed 123456: First 10 outputs - decimal seed value

Field	Value
seed	40e2010000000000
outputSize	40
input	null
expected	40e20100fd3e51964536e3a981b77780 05d90d3d686fc6b70e0ebd5f07623ccd 8a3874e58088b9ce

Vector 3 — Seed 0xDEADBEEF: First 10 outputs - hex seed value

Field	Value
seed	efbeadde00000000
outputSize	40
input	null
expected	efbeadde824a1c01fc44561708baa593 2e54e3aefa448724cd006f090be01aca effedc7a03a5c5eb

Vector 4 — Seed x=1, c=1: First 10 outputs - non-zero carry

Field	Value
seed	0100000001000000
outputSize	40
input	null
expected	000000001cb8feffccfa045c1acfbe32 4b02f33dbdc64f0e57d817ff7a3489ba ff68477c9903a06a

Vector 5 — Seed 999999: First 8 outputs - medium seed value

Field	Value
seed	3f420f0000000000
outputSize	32
input	null
expected	3f420f008e06b474b3b8662b4d8765cd94d31ed4dd1d373cb2d2ee2130b81cdb

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