Re: [chuck-users] easy random numbers

19 Nov 2007

      Pseudo-random number generator functions are easy to come by, here's
an example from "Xorshift RNGs" (Marsaglia, 2003;
http://www.jstatsoft.org/v08/i14)

2463534242 => int seed;

fun int xor(int y) {
    (y << 13) ^=> y;
    (y >> 17) => y;
    (y << 5) ^=> y;
    return y;
}

seed => int y;
while(true)
{
        1::second => now;
        xor(y) => y;
        <<<y>>>;
}

But again, you need a seed to begin with.

   michael

On Nov 19, 2007 12:52 PM, David Powers  wrote:
...
I guess you need some pseudo-random number to multiply by, such as the
system time in milliseconds... However I'm not sure how one would get
the system time into ChucK.
I suppose that you could run some sort of batch script, or say a
couple lines of Python, that either gets the current system time, or
creates some type of random seed number; then generates a ChucK file
with that seed number as a global variable.
~David
On Nov 19, 2007 12:26 PM, jakob kaiser  wrote:
...
Hi,
 I want to write a small script for ear training with Chuck. Therefore Chuck
should produce values that seem to be quite random. But it seems like that
the standard functions here are too deterministic. I know that a
non-deterministic random function would not be possible, but most
programming languages provide functions that create at least new numbers
every time I start the same code. However, in chuck something like the
following always prints the same numbers when I run it:
while(true){
   1::second => now;
   Math.rand2(50, 1000) => int rndNumber;
   <<<rndNumber>>>;
}
Is there an easy way to get something more unpredictable? I don't want to
go deep into random generator programming. But the function does not really
what you would expect of a random generator, does it?
Cheers
Jakob

Re: [chuck-users] easy random numbers

Michael Heuer