Random Number Generation.

Anon

Hi all.

Has anyone found a solution to the problem of generating truly random numbers as opposed to pseudo-random?

Thanks.

[deleted]

Depends on what you find pseudo-random.
Seeding the generator with the current makes it pretty random :-)

Anon

The thing about random numbers is this: if you define a method by which to find random numbers, those numbers are no longer random. The definition of a random number is one that cannot be predicted, however, with a function or method, by definition, one is able to predict the result.

So, with any algorithm used to generate random numbers, the numbers will always be psuedo-random.

There are theories about ways to generate truly random numbers though. Those ways include pulling in some portion of a random radio signal and converting it to a number, or pulling off some random packet data off the internet and converting it into a number. Then, however, one has to be sure that every number (within reason) has an equally probable chance of showing up in the radio signal or internet data--this is something that cannot generally be assured.

[deleted]

You contradict yourself :-)

"if you define a method by which to find random numbers, those numbers are no longer random."

But...

"Those ways include pulling in some portion of a random radio signal and converting it to a number"

So you can define a method and have it be random. :-)

BTW, a simple "white-noise" generator will do the same, much more random than radio waves.

Anon

Hi.

You could always use random.org as a source. If that doesn't appeal to you, simply connect a microphone to your computer and a radio ( tuned to a station where no one is broadcasting ) and sample the sound it receives.

-Katie.

Anon

$ranorg = fopen ("http://www.random.org/cgi-bin/randnum?num=1&min=100&max=200&col=1","r");
$rannum = fread ($ranorg,4096);
fclose($ranorg);

That takes a random number, from 100 - 200, from random.org. Check out their site for more info. They are adding more features soon.

Not sure if that will be any help to you but I've used it sucessfully in scripts before.

Gavin Riggott

[deleted]

Doesn't that kind of reduce your performance to near zero? And what if that site is unreachable?

Anon

On average it adds a second or two to the process time (random.org is designed so that remote scripts can pull the info from their site afterall). To answer your other question, if the site is down then no random numbers will be generated.

This is unfortunate, true, but what is the alternative? If you want true random numbers then standard PHP random number functions won't do; you have to use something else, such as white noise. Random.org is convenient and easy to use (and free), but if you have a way to generate your own numbers then that is of course preferable.

Of course, if you don't mind using pseudo-random numbers (which are fine for most applications), then use PHP on its own.

Gavin Riggott

vincent wrote:

Doesn't that kind of reduce your performance to near zero? And what if that site is unreachable?

[deleted]

I guess it's handy in some exotic applications. However, I'd sooner create a random number generator on my own server than use an 'unreliable' external source. especially as it takes 2 seconds or more to even get the number. (I can imagine I could need 10 of them, that would give an unacceptably low performance)