Documentation
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Overview ¶
Package xoroshiro provides an implementation for a pseudo-random number generator (PRNG) using the xoroshiro128** and xoroshiro128+ algorithms.
Period: 2^128-1. State size: 128 bits.
Go implementation based on a C reference implementation by David Blackman and Sebastiano Vigna. For further information: http://xoshiro.di.unimi.it/
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Rng128P ¶
type Rng128P struct {
// contains filtered or unexported fields
}
Rng128P encapsulates a xoroshiro128+ PRNG.
xoroshiro128+ 1.0 is Blackman & Vigna's best and fastest small-state generator for floating-point numbers. They suggest to use its upper bits for floating-point generation, as it is slightly faster than xoroshiro128**. It passes all tests the authors are aware of except for the four lower bits, which might fail linearity tests (and just those), so if low linear complexity is not considered an issue (as it is usually the case) it can be used to generate 64-bit outputs, too; moreover, this generator has a very mild Hamming-weight dependency making our test (http://prng.di.unimi.it/hwd.php) fail after 5 TB of output; the authors believe this slight bias cannot affect any application. If you are concerned, use xoroshiro128** or xoshiro256+.
The authors suggest to use a sign test to extract a random Boolean value, and right shifts to extract subsets of bits.
Note that the Go implementation of Rand.Float64 uses the upper bits as suggested.
Example ¶
package main
import (
"fmt"
"math/rand"
"github.com/db47h/rand64/v3/xoroshiro"
)
const SEED1 = 1387366483214
func main() {
src := xoroshiro.Rng128P{}
src.Seed(SEED1)
rng := rand.New(&src)
for i := 0; i < 4; i++ {
fmt.Printf(" %d", rng.Uint32())
}
fmt.Println("")
for i := 0; i < 4; i++ {
fmt.Printf(" %d", rng.Uint64())
}
fmt.Println("")
// Play craps
for i := 0; i < 10; i++ {
fmt.Printf(" %d%d", rng.Intn(6)+1, rng.Intn(6)+1)
}
}
Output: 3672052799 776653214 1122818236 1139848352 14850484681238877506 7018105211938886447 5908230704518956940 2042158984393296588 65 53 21 56 44 16 23 42 55 41
type Rng128SS ¶
type Rng128SS struct {
// contains filtered or unexported fields
}
Rng128SS encapsulates a xoroshiro128** PRNG.
xoroshiro128** 1.0 is Blackman & Vigna's all-purpose, rock-solid, small-state generator. It is extremely (sub-ns) fast and it passes all tests the authors are aware of, but its state space is large enough only for mild parallelism.
For generating just floating-point numbers, xoroshiro128+ is even faster (but it has a very mild bias, see notes in the comments).
Example ¶
package main
import (
"fmt"
"math/rand"
"github.com/db47h/rand64/v3/xoroshiro"
)
const SEED1 = 1387366483214
func main() {
src := xoroshiro.Rng128SS{}
src.Seed(SEED1)
rng := rand.New(&src)
for i := 0; i < 4; i++ {
fmt.Printf(" %d", rng.Uint32())
}
fmt.Println("")
for i := 0; i < 4; i++ {
fmt.Printf(" %d", rng.Uint64())
}
fmt.Println("")
// Play craps
for i := 0; i < 10; i++ {
fmt.Printf(" %d%d", rng.Intn(6)+1, rng.Intn(6)+1)
}
}
Output: 901646676 398979522 1208087553 1093404254 17905646702528074117 5693647338227160345 1089260090730707711 12276528025967720504 41 35 56 61 56 35 31 12 63 54
Source Files