My PCG library's 32-bit generator generates a 32-bit pseudo-random integer
in 2.23 ns.
https://github.com/MichaelTJones/pcg
Just wrote this 32-bit float extension and that delivers a float32 in 2.75
ns. (363 million/good values/sec, period of 2**64 = 4 billion). The extra
time is for the multiply:
func (p *PCG32) Float32() float32 {
const bits = 23
const denom = 1.0 / float32(1<<bits)
return float32(p.Random()>>(32-bits)) * denom
}
The same thing, but with the 2**128 period generator is 6.91 ns/op per
float32
If you want faster than that then you'll need to look at other ways, likely
non-multiply ways.
IMPORTANT...
Also, be reminded that generating "random real values in [0..1)" is not the
same thing as "random floating point values in [0..1)".
it is subtle, and it seems you may want the former, but a random sampling
of float32's in that range would be different, using the exponent to scale
the 8 million possible mantissa fractions to various tiny ranges. There are
4 billion values total. so som big subsetting is happening.
On Mon, Feb 25, 2019 at 2:05 PM Ian Lance Taylor <i...@golang.org> wrote:
> On Mon, Feb 25, 2019 at 2:01 PM DrGo <salah.mah...@gmail.com> wrote:
> >
> > what is the fastest possible algorithm to generate a float32
> pseudo-random number in [0.0,1.0)?
> > need to generate billions of numbers. Statistical performance and
> security (and even space) are not a priority.
> > any Go implementations you know of?
>
> Take a look at https://godoc.org/golang.org/x/exp/rand .
>
> Ian
>
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--
*Michael T. jonesmichael.jo...@gmail.com <michael.jo...@gmail.com>*
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