Re: Speed of Random Numbers
On Sun, Aug 4, 2019 at 11:49 AM Daniel Kozak wrote: > > You can try http://code.dlang.org/packages/mir-random > > I am using theme here: > https://github.com/TechEmpower/FrameworkBenchmarks/blob/b9cc153dcd1c20e78197b0191536f0d11b8ca554/frameworks/D/vibed/source/postgresql.d#L49 > > On Sun, Aug 4, 2019 at 12:20 AM Giovanni Di Maria via > Digitalmars-d-learn wrote: > > > > Thank you very much to Everybody! > > Giovanni > > You can try http://code.dlang.org/packages/mir-random I am using theme here: https://github.com/TechEmpower/FrameworkBenchmarks/blob/b9cc153dcd1c20e78197b0191536f0d11b8ca554/frameworks/D/vibed/source/postgresql.d#L49 And compile it with ldc
Re: Speed of Random Numbers
You can try http://code.dlang.org/packages/mir-random I am using theme here: https://github.com/TechEmpower/FrameworkBenchmarks/blob/b9cc153dcd1c20e78197b0191536f0d11b8ca554/frameworks/D/vibed/source/postgresql.d#L49 On Sun, Aug 4, 2019 at 12:20 AM Giovanni Di Maria via Digitalmars-d-learn wrote: > > Thank you very much to Everybody! > Giovanni >
Re: Speed of Random Numbers
Thank you very much to Everybody! Giovanni
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria
wrote:
For me the "goodness of random" is NOT important.
If that's the case, you could roll your own RNG:
//DMD64 D Compiler 2.072.2
import std.stdio;
import std.datetime;
import std.array, std.random;
void main(){
ubyte x;
auto r = benchmark!(f1,f2)(10_000);
writeln(r[0]);
writeln(r[1]);
}
int f1(){
static s = 10; // Seed
s = (214013*s+2531011); // [1]
s = (s>>16)&0x7FFF;
auto y=(s&7)+1;
//writeln(y);
return y;
}
int f2(){
byte c;
c=uniform!ubyte() % 8 +1;
//writeln(c);
return c;
}
/*
[1]
https://software.intel.com/en-us/articles/fast-random-number-generator-on-the-intel-pentiumr-4-processor/
*/
/*
OUTPUT:
TickDuration(65263) <-f1
TickDuration(635167) <-f2
*/
Matheus.
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 17:47:46 UTC, Giovanni Di Maria
wrote:
On Saturday, 3 August 2019 at 17:44:44 UTC, lithium iodate
wrote:
On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria
wrote:
[...]
First off you could try to use a faster RNG engine than the
default. The easiest way is to define a variable containing it
and passing it to the functions each time.
auto rng = Xorshift(1234);
randomNumber = uniform!uint(rng);
This basic change approximately halved the 5 seconds your
original example needs on my computer.
Another simple approach that I have tried is simply hashing
the iterator using a fast hash function.
With xxHash32 I got the time down to 0.25 seconds. I also
tried xxHash64 and FNV1a but they were not faster in my quick
test.
Thank you very much Lithium Iodate
Now i will try it.
I let know you.
Thank you
Giovanni
If it doesn't matter if it's predictable or not then you could
easily make your own simple random generator with would give
"random" results.
Of course in general it's not usable:
import std.stdio;
class Random
{
private:
uint _seed;
uint _interval;
T abs(T)(T x)
{
T y = x > 0 ? T.max : cast(T)0;
return (x ^ y) - y;
}
public:
this()
{
import core.stdc.time;
_seed = cast(uint)time(null);
_interval = (_seed - 20559);
}
T next(T)(T max)
{
auto value = cast(T)(abs(_interval) % T.max);
_interval -= (_interval / 10) * _seed;
return value;
}
}
void main()
{
auto random = new Random;
foreach (_; 0 .. 1000)
{
auto result = random.next!ubyte(255);
writeln(result);
}
}
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria
wrote:
Do you know other faster functions or methods to generate
random numbers?
For me the "goodness of random" is NOT important.
I found some nice random functions in this public-domain C
single-header library collection, one of which is GameRand:
https://github.com/mattiasgustavsson/libs/blob/022370a79cf2d5f87fb43b420834a069adb5fede/rnd.h#L449
Here's the D version:
```
struct GameRand
{
uint[2] state;
}
uint randomGameRand(ref GameRand gamerand) {
gamerand.state[0] = ( gamerand.state[0] << 16 ) + (
gamerand.state[0] >> 16 );
gamerand.state[0] += gamerand.state[1];
gamerand.state[1] += gamerand.state[0];
return gamerand.state[0];
}
```
It's really fast and decent enough for games (hence the name I
suppose). See:
http://www.flipcode.com/archives/07-15-2002.shtml
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 17:44:44 UTC, lithium iodate wrote: On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria wrote: [...] First off you could try to use a faster RNG engine than the default. The easiest way is to define a variable containing it and passing it to the functions each time. auto rng = Xorshift(1234); randomNumber = uniform!uint(rng); This basic change approximately halved the 5 seconds your original example needs on my computer. Another simple approach that I have tried is simply hashing the iterator using a fast hash function. With xxHash32 I got the time down to 0.25 seconds. I also tried xxHash64 and FNV1a but they were not faster in my quick test. Thank you very much Lithium Iodate Now i will try it. I let know you. Thank you Giovanni
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria wrote: Do you know other faster functions or methods to generate random numbers? For me the "goodness of random" is NOT important. Thank you very much GIovanni Di Maria First off you could try to use a faster RNG engine than the default. The easiest way is to define a variable containing it and passing it to the functions each time. auto rng = Xorshift(1234); randomNumber = uniform!uint(rng); This basic change approximately halved the 5 seconds your original example needs on my computer. Another simple approach that I have tried is simply hashing the iterator using a fast hash function. With xxHash32 I got the time down to 0.25 seconds. I also tried xxHash64 and FNV1a but they were not faster in my quick test.
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 17:17:23 UTC, Cym13 wrote: On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria wrote: [...] To what extent isn't the quality of randomness important to you? Your posts reminds me of the way Doom (the original) did it for things like enemy behaviour and shot dispersion: they generated a static table of 256 random numbers once and any time they needed a random byte they just picked the next in the table. They didn't have any security or sciency concern and just wanted to provide a different game each time so that worked well for them. You won't find anything faster than that I think. Exactly Cym13. The important is to get a different number Ok, thank you. G
Re: Speed of Random Numbers
On Saturday, 3 August 2019 at 16:35:34 UTC, Giovanni Di Maria
wrote:
Hi to everybody
I am doing some experiments about random numbers.
I need "extreme speed" for the generation for numbers from 1 to
8.
Generating 500_000_000 numbers with this code:
-
import std.stdio, std.array, std.random;
void main()
{
byte c;
writeln("Start");
for(int k=1;k<=500_000_000;k++)
c=uniform!ubyte() % 8 +1; //<<< === RANDOM
writeln("Stop");
}
-
I get these results:
c=uniform!ubyte() % 8 +1; ==>>> Execution time: 15.563 s
c=cast(byte)uniform(1, 9); ==>>> Execution time: 24.218 s
Do you know other faster functions or methods to generate
random numbers?
For me the "goodness of random" is NOT important.
Thank you very much
GIovanni Di Maria
To what extent isn't the quality of randomness important to you?
Your posts reminds me of the way Doom (the original) did it for
things like enemy behaviour and shot dispersion: they generated a
static table of 256 random numbers once and any time they needed
a random byte they just picked the next in the table. They didn't
have any security or sciency concern and just wanted to provide a
different game each time so that worked well for them. You won't
find anything faster than that I think.
Speed of Random Numbers
Hi to everybody
I am doing some experiments about random numbers.
I need "extreme speed" for the generation for numbers from 1 to 8.
Generating 500_000_000 numbers with this code:
-
import std.stdio, std.array, std.random;
void main()
{
byte c;
writeln("Start");
for(int k=1;k<=500_000_000;k++)
c=uniform!ubyte() % 8 +1; //<<< === RANDOM
writeln("Stop");
}
-
I get these results:
c=uniform!ubyte() % 8 +1; ==>>> Execution time: 15.563 s
c=cast(byte)uniform(1, 9); ==>>> Execution time: 24.218 s
Do you know other faster functions or methods to generate random
numbers?
For me the "goodness of random" is NOT important.
Thank you very much
GIovanni Di Maria
