math/rand: mention half-open intervals explicitly
If someone sees "in [0,n)" it might look like a typo.
Saying "in the half-open interval [0,n)" will give people
something to search the web for (half-open interval).
Change-Id: I3c343f0a7171891e106e709ca77ab9db5daa5c84
Reviewed-on: https://go-review.googlesource.com/c/go/+/328210
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/src/math/rand/rand.go b/src/math/rand/rand.go
index 8179d9f..13f20ca 100644
--- a/src/math/rand/rand.go
+++ b/src/math/rand/rand.go
@@ -12,9 +12,6 @@
// The default Source is safe for concurrent use by multiple goroutines, but
// Sources created by NewSource are not.
//
-// Mathematical interval notation such as [0, n) is used throughout the
-// documentation for this package.
-//
// This package's outputs might be easily predictable regardless of how it's
// seeded. For random numbers suitable for security-sensitive work, see the
// crypto/rand package.
@@ -106,7 +103,7 @@
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).
+// Int63n returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n).
// It panics if n <= 0.
func (r *Rand) Int63n(n int64) int64 {
if n <= 0 {
@@ -123,7 +120,7 @@
return v % n
}
-// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
+// Int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n).
// It panics if n <= 0.
func (r *Rand) Int31n(n int32) int32 {
if n <= 0 {
@@ -140,7 +137,7 @@
return v % n
}
-// int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
+// int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n).
// n must be > 0, but int31n does not check this; the caller must ensure it.
// int31n exists because Int31n is inefficient, but Go 1 compatibility
// requires that the stream of values produced by math/rand remain unchanged.
@@ -164,7 +161,7 @@
return int32(prod >> 32)
}
-// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
+// Intn returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n).
// It panics if n <= 0.
func (r *Rand) Intn(n int) int {
if n <= 0 {
@@ -176,7 +173,7 @@
return int(r.Int63n(int64(n)))
}
-// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
+// Float64 returns, as a float64, a pseudo-random number in the half-open interval [0.0,1.0).
func (r *Rand) Float64() float64 {
// A clearer, simpler implementation would be:
// return float64(r.Int63n(1<<53)) / (1<<53)
@@ -202,7 +199,7 @@
return f
}
-// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
+// Float32 returns, as a float32, a pseudo-random number in the half-open interval [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
@@ -215,7 +212,8 @@
return f
}
-// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
+// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers
+// in the half-open interval [0,n).
func (r *Rand) Perm(n int) []int {
m := make([]int, n)
// In the following loop, the iteration when i=0 always swaps m[0] with m[0].
@@ -323,31 +321,31 @@
// 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)
+// Int63n returns, as an int64, a non-negative pseudo-random number in the half-open interval [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)
+// Int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [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)
+// Intn returns, as an int, a non-negative pseudo-random number in the half-open interval [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)
+// Float64 returns, as a float64, a pseudo-random number in the half-open interval [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)
+// Float32 returns, as a float32, a pseudo-random number in the half-open interval [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.
+// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers
+// in the half-open interval [0,n) from the default Source.
func Perm(n int) []int { return globalRand.Perm(n) }
// Shuffle pseudo-randomizes the order of elements using the default Source.
