Just an ignorant assumption, but would not the output of [noise~]
itself be generated from pseudo-random numbers? If not, then how does
[noise~] generate its randomness? Or is there something more complex
at work?
Ian
On 05/07/2009, at 7:12 PM, Andrew Faraday wrote:
Just an idea, but if the hardware random number generators use a
jittery oscillator etc. Why not use [noise~] and [snapshot~]
followed by some arithmetic and [int] you could build what I assume
would be more random than the [random] box.Andrew
Date: Sun, 5 Jul 2009 00:22:51 -0400 From: martin.peach@sympatico.ca To: mmoserbooth@gmail.com CC: pd-list@iem.at; zmoelnig@iem.at Subject: Re: [PD] help_random/seed
Mike Moser-Booth wrote:
IOhannes m zmölnig wrote:
Frank Barknecht wrote:
Hallo, cem guney hat gesagt: // cem guney wrote:
just started studying PD. going through the control examples
i've
been stuck trying to figure out the function of the message,
seed
123 in the example for "random". not sure if i figured out the
explanation below,
Seeds are kept locally so that if two Randoms are seeded the
same
they will have the same output (or indeed you can seed the
same one
twice to repeat the output.)
Yes, that's true, you understood correctly.
Oh, wait, that's what's in the help-file! What exactly is
cloudy there?
probably the simple fact, that [random] despite of it's name
does not
really produce random numbers. mostly when computers present you a "random" number, then this
number
will only appear to be random, but in reality is just
calculated as
the next item of a totally deterministic series. (as a matter of fact, a new random number is usually generated by simple taking the last number and then applying some more or less complicated transformation on this number). this method is
known as
"pseudo random".
you can set the "starting point" of the series by setting the
"seed",
which is the first number of the random sequence). since all
[random]
object use the same algorithm to calculate the next pseudo-random number, they will all end up with the same sequence if they all
start
with the same "seed". by default Pd uses different seeds for all [random] objects so
they
all appear to work independently.
In addition, it's probably worth mentioning that Pd will produce
the
same seeds for each [random] every time you load the patch. So
while
they appear to work independently, you will still get the same
results
each time you first run a patch after loading it.
A lot of the latest cpus have hardware random number generators that work by having a jittery oscillator sample the cpu clock, or
something
along those lines. (Such a jittery oscillator is assumed to have normally distributed transition times.) It would be nice if the random source could be independently
specified
for all the pd objects that use random numbers, since the count of unreachable combinations when using the standard deterministic chaos generators is infinite.
Martin
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