README
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rand
Additional Sources for Go's math/rand
- SplitMix64 - period 2^64
- XOshiro256 - period 2^256 - 1
- PCG XSL RR 128/64 (LCG) - period 2^128
Documentation
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Overview ¶
Package rand contains additional math/rand/Source64 implementations for use with math/rand's Rand type.
The standard math/rand Source64 pre v1.17 used an Additive Lagged Fibonacci Generator (ALFG) originally designed by DP Mitchell and JA Reeds for Bell Lab's Plan9 operating system. From 1.17 it uses the wyrand (runtime.fastrand) PRNG https://github.com/wangyi-fudan/wyhash
SplitMix64 (period 2^64)
A fixed-increment version of Java 8's SplittableRandom generator See http://dx.doi.org/10.1145/2714064.2660195 and http://docs.oracle.com/javase/8/docs/api/java/util/SplittableRandom.html It is a very fast generator passing BigCrush, and it can be useful if for some reason you absolutely want 64 bits of state; otherwise, we rather suggest to use a xoroshiro128+ (for moderately parallel computations) or xorshift1024* (for massively parallel computations) generator. - Sebastiano Vigna
XOshiro256 (xoshiro256** in the literature) (period 2^256 - 1)
According to Vigna, this is faster and produces better output than the xorshift family of generators. (See https://en.wikipedia.org/wiki/Xorshift and https://prng.di.unimi.it/)
PCG (Permuted Congruential Generator) (period 2^128)
An implementation of the PCG XSL RR 128/64 (LCG) generator described in Melissa O'Neill's paper. (See http://www.pcg-random.org/pdf/toms-oneill-pcg-family-v1.02.pdf) There's an alternative implementation in golang.org/x/exp/rand.
Relative speeds (not very scientific)
Without/with locking SplitMix64 0.345/1.540 XOshiro256 0.379/1.717 ALFG 0.429/1.748 PCG 0.454/1.728
The statistical testing suite Big Crush/TU01 is described at http://simul.iro.umontreal.ca/testu01/tu01.html and available at https://github.com/umontreal-simul/TestU01-2009/
Index ¶
Constants ¶
const (
// MaxUint63 represents the largest value that can be held in a 63 bit unsigned integer.
MaxUint63 = (1 << 63) - 1
)
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type LockableSource ¶
type LockableSource struct {
// contains filtered or unexported fields
}
LockableSource wraps a type implementing rand.Source64 in a mutex to make it goroutine safe.
func NewLockableSource ¶
func NewLockableSource(src rand.Source64) *LockableSource
NewLockableSource returns src wrapped in a mutex.
func (*LockableSource) Int63 ¶
func (s *LockableSource) Int63() int64
Int63 implements the rand.Source interface.
func (*LockableSource) Seed ¶
func (s *LockableSource) Seed(seed int64)
Seed implements the rand.Source interface.
func (*LockableSource) Uint64 ¶
func (s *LockableSource) Uint64() uint64
Uint64 implements the rand.Source64 interface.
type PCGSource ¶
type PCGSource [2]uint64
PCGSource - size 128 bits, period 2^128.
type SplitMix64Source ¶
type SplitMix64Source uint64
SplitMix64Source - size 64 bits, period 2^64.
func (*SplitMix64Source) Int63 ¶
func (s *SplitMix64Source) Int63() int64
Int63 implements the rand.Source interface.
func (*SplitMix64Source) Seed ¶
func (s *SplitMix64Source) Seed(seed int64)
Seed implements the rand.Source interface.
func (*SplitMix64Source) Uint64 ¶
func (s *SplitMix64Source) Uint64() uint64
Uint64 implements the rand.Source64 interface.
type WySource ¶
type WySource uint64
WySource (from https://github.com/wangyi-fudan/wyhash)
type XOshiro256Source ¶
type XOshiro256Source [4]uint64
XOshiro256Source - size 256 bits, period 2^256 - 1. Do not leave zero initialized!
func (*XOshiro256Source) Int63 ¶
func (s *XOshiro256Source) Int63() int64
Int63 implements the rand.Source interface.
func (*XOshiro256Source) Jump ¶
func (s *XOshiro256Source) Jump() *XOshiro256Source
Jump is equivalent to 2^128 calls to Uint64(); it can be used to generate 2^128 non-overlapping subsequences for parallel computations.
func (*XOshiro256Source) LongJump ¶
func (s *XOshiro256Source) LongJump() *XOshiro256Source
LongJump is equivalent to 2^192 calls to Uint64(); it can be used to generate 2^64 starting points, from each of which jump() will generate 2^64 non-overlapping subsequences for parallel distributed computations.
func (*XOshiro256Source) Seed ¶
func (s *XOshiro256Source) Seed(seed int64)
Seed implements the rand.Source interface.
func (*XOshiro256Source) Uint64 ¶
func (s *XOshiro256Source) Uint64() uint64
Uint64 implements the rand.Source64 interface.
Source Files