summaryrefslogtreecommitdiff
path: root/src/pkg/math/rand/rand.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/pkg/math/rand/rand.go')
-rw-r--r--src/pkg/math/rand/rand.go246
1 files changed, 0 insertions, 246 deletions
diff --git a/src/pkg/math/rand/rand.go b/src/pkg/math/rand/rand.go
deleted file mode 100644
index 3ffb5c4e5..000000000
--- a/src/pkg/math/rand/rand.go
+++ /dev/null
@@ -1,246 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package rand implements pseudo-random number generators.
-//
-// Random numbers are generated by a Source. Top-level functions, such as
-// Float64 and Int, use a default shared Source that produces a deterministic
-// sequence of values each time a program is run. Use the Seed function to
-// initialize the default Source if different behavior is required for each run.
-// The default Source is safe for concurrent use by multiple goroutines.
-package rand
-
-import "sync"
-
-// A Source represents a source of uniformly-distributed
-// pseudo-random int64 values in the range [0, 1<<63).
-type Source interface {
- Int63() int64
- Seed(seed int64)
-}
-
-// NewSource returns a new pseudo-random Source seeded with the given value.
-func NewSource(seed int64) Source {
- var rng rngSource
- rng.Seed(seed)
- return &rng
-}
-
-// A Rand is a source of random numbers.
-type Rand struct {
- src Source
-}
-
-// New returns a new Rand that uses random values from src
-// to generate other random values.
-func New(src Source) *Rand { return &Rand{src} }
-
-// Seed uses the provided seed value to initialize the generator to a deterministic state.
-func (r *Rand) Seed(seed int64) { r.src.Seed(seed) }
-
-// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
-func (r *Rand) Int63() int64 { return r.src.Int63() }
-
-// Uint32 returns a pseudo-random 32-bit value as a uint32.
-func (r *Rand) Uint32() uint32 { return uint32(r.Int63() >> 31) }
-
-// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
-func (r *Rand) Int31() int32 { return int32(r.Int63() >> 32) }
-
-// Int returns a non-negative pseudo-random int.
-func (r *Rand) Int() int {
- u := uint(r.Int63())
- return int(u << 1 >> 1) // clear sign bit if int == int32
-}
-
-// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n).
-// It panics if n <= 0.
-func (r *Rand) Int63n(n int64) int64 {
- if n <= 0 {
- panic("invalid argument to Int63n")
- }
- if n&(n-1) == 0 { // n is power of two, can mask
- return r.Int63() & (n - 1)
- }
- max := int64((1 << 63) - 1 - (1<<63)%uint64(n))
- v := r.Int63()
- for v > max {
- v = r.Int63()
- }
- return v % n
-}
-
-// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
-// It panics if n <= 0.
-func (r *Rand) Int31n(n int32) int32 {
- if n <= 0 {
- panic("invalid argument to Int31n")
- }
- if n&(n-1) == 0 { // n is power of two, can mask
- return r.Int31() & (n - 1)
- }
- max := int32((1 << 31) - 1 - (1<<31)%uint32(n))
- v := r.Int31()
- for v > max {
- v = r.Int31()
- }
- return v % n
-}
-
-// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
-// It panics if n <= 0.
-func (r *Rand) Intn(n int) int {
- if n <= 0 {
- panic("invalid argument to Intn")
- }
- if n <= 1<<31-1 {
- return int(r.Int31n(int32(n)))
- }
- return int(r.Int63n(int64(n)))
-}
-
-// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
-func (r *Rand) Float64() float64 {
- // A clearer, simpler implementation would be:
- // return float64(r.Int63n(1<<53)) / (1<<53)
- // However, Go 1 shipped with
- // return float64(r.Int63()) / (1 << 63)
- // and we want to preserve that value stream.
- //
- // There is one bug in the value stream: r.Int63() may be so close
- // to 1<<63 that the division rounds up to 1.0, and we've guaranteed
- // that the result is always less than 1.0. To fix that, we treat the
- // range as cyclic and map 1 back to 0. This is justified by observing
- // that while some of the values rounded down to 0, nothing was
- // rounding up to 0, so 0 was underrepresented in the results.
- // Mapping 1 back to zero restores some balance.
- // (The balance is not perfect because the implementation
- // returns denormalized numbers for very small r.Int63(),
- // and those steal from what would normally be 0 results.)
- // The remapping only happens 1/2⁵³ of the time, so most clients
- // will not observe it anyway.
- f := float64(r.Int63()) / (1 << 63)
- if f == 1 {
- f = 0
- }
- return f
-}
-
-// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
-func (r *Rand) Float32() float32 {
- // Same rationale as in Float64: we want to preserve the Go 1 value
- // stream except we want to fix it not to return 1.0
- // There is a double rounding going on here, but the argument for
- // mapping 1 to 0 still applies: 0 was underrepresented before,
- // so mapping 1 to 0 doesn't cause too many 0s.
- // This only happens 1/2²⁴ of the time (plus the 1/2⁵³ of the time in Float64).
- f := float32(r.Float64())
- if f == 1 {
- f = 0
- }
- return f
-}
-
-// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
-func (r *Rand) Perm(n int) []int {
- m := make([]int, n)
- for i := 0; i < n; i++ {
- j := r.Intn(i + 1)
- m[i] = m[j]
- m[j] = i
- }
- return m
-}
-
-/*
- * Top-level convenience functions
- */
-
-var globalRand = New(&lockedSource{src: NewSource(1)})
-
-// Seed uses the provided seed value to initialize the default Source to a
-// deterministic state. If Seed is not called, the generator behaves as
-// if seeded by Seed(1).
-func Seed(seed int64) { globalRand.Seed(seed) }
-
-// Int63 returns a non-negative pseudo-random 63-bit integer as an int64
-// from the default Source.
-func Int63() int64 { return globalRand.Int63() }
-
-// Uint32 returns a pseudo-random 32-bit value as a uint32
-// from the default Source.
-func Uint32() uint32 { return globalRand.Uint32() }
-
-// Int31 returns a non-negative pseudo-random 31-bit integer as an int32
-// from the default Source.
-func Int31() int32 { return globalRand.Int31() }
-
-// Int returns a non-negative pseudo-random int from the default Source.
-func Int() int { return globalRand.Int() }
-
-// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n)
-// from the default Source.
-// It panics if n <= 0.
-func Int63n(n int64) int64 { return globalRand.Int63n(n) }
-
-// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n)
-// from the default Source.
-// It panics if n <= 0.
-func Int31n(n int32) int32 { return globalRand.Int31n(n) }
-
-// Intn returns, as an int, a non-negative pseudo-random number in [0,n)
-// from the default Source.
-// It panics if n <= 0.
-func Intn(n int) int { return globalRand.Intn(n) }
-
-// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0)
-// from the default Source.
-func Float64() float64 { return globalRand.Float64() }
-
-// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0)
-// from the default Source.
-func Float32() float32 { return globalRand.Float32() }
-
-// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n)
-// from the default Source.
-func Perm(n int) []int { return globalRand.Perm(n) }
-
-// NormFloat64 returns a normally distributed float64 in the range
-// [-math.MaxFloat64, +math.MaxFloat64] with
-// standard normal distribution (mean = 0, stddev = 1)
-// from the default Source.
-// To produce a different normal distribution, callers can
-// adjust the output using:
-//
-// sample = NormFloat64() * desiredStdDev + desiredMean
-//
-func NormFloat64() float64 { return globalRand.NormFloat64() }
-
-// ExpFloat64 returns an exponentially distributed float64 in the range
-// (0, +math.MaxFloat64] with an exponential distribution whose rate parameter
-// (lambda) is 1 and whose mean is 1/lambda (1) from the default Source.
-// To produce a distribution with a different rate parameter,
-// callers can adjust the output using:
-//
-// sample = ExpFloat64() / desiredRateParameter
-//
-func ExpFloat64() float64 { return globalRand.ExpFloat64() }
-
-type lockedSource struct {
- lk sync.Mutex
- src Source
-}
-
-func (r *lockedSource) Int63() (n int64) {
- r.lk.Lock()
- n = r.src.Int63()
- r.lk.Unlock()
- return
-}
-
-func (r *lockedSource) Seed(seed int64) {
- r.lk.Lock()
- r.src.Seed(seed)
- r.lk.Unlock()
-}