rng

Documentation

Overview

Package rng provides deterministic random number generation with hierarchical seed derivation.

The Derive function creates child seeds from parent seeds using FNV-1a hashing, enabling reproducible randomness across nested contexts (entity → field → row). This ensures that the same plan with the same root seed always produces identical output, which is critical for Apery's determinism guarantees.

Index

• type Rng
  • func New(seed Seed) *Rng
  • func (r *Rng) Float64() float64
  • func (r *Rng) FloatRange(min float64, max float64) float64
  • func (r *Rng) GetSeed() Seed
  • func (r *Rng) IntRange(min int64, max int64) int64
  • func (r *Rng) Intn(n int) int
  • func (r *Rng) NewZipf(s float64, v float64, imax uint64) *rand.Zipf
  • func (r *Rng) NormFloat64() float64
  • func (r *Rng) Read(p []byte) (int, error)
• type Seed
  • func Derive(parent Seed, label string) Seed
  • func DeriveIndex(parent Seed, index int64) Seed
  • func SeedFromInt64(value int64) Seed

Types

type Rng

type Rng struct {
	// contains filtered or unexported fields
}

Rng is a seeded random number generator

func New

func New(seed Seed) *Rng

New creates a new RNG with a seed.

func (*Rng) Float64

func (r *Rng) Float64() float64

Float64 returns a random float in [0,1.0)

func (*Rng) FloatRange

func (r *Rng) FloatRange(min float64, max float64) float64

FloatRange returns a random float64 in [min, max]

func (*Rng) GetSeed

func (r *Rng) GetSeed() Seed

GetSeed returns rng seed

func (*Rng) IntRange

func (r *Rng) IntRange(min int64, max int64) int64

IntRange returns a random int64 in [min, max]

func (*Rng) Intn

func (r *Rng) Intn(n int) int

Intn returns a random int in [0,n)

func (*Rng) NewZipf

func (r *Rng) NewZipf(s float64, v float64, imax uint64) *rand.Zipf

NewZipf creates a Zipf generator with skewness s, offset v, and max value imax. s must be > 1, v must be >= 1

func (*Rng) NormFloat64

func (r *Rng) NormFloat64() float64

NormFloat64 returns a normally distributed float64 with mean 0 and stddev 1 using the Box-Muller transform

func (*Rng) Read

func (r *Rng) Read(p []byte) (int, error)

Read fills p with random bytes, implementing io.Reader

type Seed

type Seed uint64

Seed represents a deterministic RNG seed.

func Derive

func Derive(parent Seed, label string) Seed

Derive creates a child seed from parent + label.

func DeriveIndex

func DeriveIndex(parent Seed, index int64) Seed

DeriveIndex creates a child seed from parent + index.

func SeedFromInt64

func SeedFromInt64(value int64) Seed

SeedFromInt64 converts an int64 seed into a Seed.