Comment On More Entropy, Please

GettinSadda:

But... rand() & 16 is either 0 or 16!

GettinSadda:

But... rand() & 16 is either 0 or 16!

TheRider:

Does a higher entropy mean more ordered? or less ordered? Ouch, I'm getting chaos in my head. This looks all random to me.

int function random() {

    //definite random value as defined by a dice roll

    return 4;

}

ahnfelt:

http://xkcd.com/221/ of course ;-)

EDIT: Ok, beaten to it twice!

TheRider:

This reminds me of the much easier implementation I have seen somewhere (but, alas, can't remember where):

int function random() {

    //definite random value as defined by a dice roll

    return 4;

}

ahnfelt:

http://xkcd.com/221/ of course ;-)

EDIT: Ok, beaten to it twice!

DaveAronson:

There are assorted tests for how random a RNG/PRNG's output is.

DaveAronson:

Just in case some people may not be clear on the need for "random" numbers to be as close to really random as possible:

In most applications, like Windows solitaire or even playing good ol' rogue, it doesn't really matter. BUT, I'm sure many of us could think of scenarios where someone could take your money/secrets/whatever by predicting the "random" number. For example, generating crypto keys, or dealing cards in an online gambling site. In such cases, you don't want to settle for plain old "rand() seeded with the time". Most trivial psuedo-random-number generators (PRNGs) are so mechanistic that given a few outputs, the next output can be predicted with high confidence. Usually it's a simple function of the previous value. A more-random (i.e., closer to truly random) generator will incorporate additional "entropy" (no I'm not going to explain that). There are assorted tests for how random a RNG/PRNG's output is.

Bernie:

Cloud computing sounds random to me; we should obviously hit the network whenever we need a random value.

tag:

Rnd():

This is just a random comment

TheRider:

Bernie:

Cloud computing sounds random to me; we should obviously hit the network whenever we need a random value.

Now you're talking. Hit Google with a random query and hash the results html page. This should give you a truly random number.

abx:

TheRider:

Bernie:

Cloud computing sounds random to me; we should obviously hit the network whenever we need a random value.

Now you're talking. Hit Google with a random query and hash the results html page. This should give you a truly random number.

With a random query, eh? Recursive entropy.

TheRider:

Bernie:

Cloud computing sounds random to me; we should obviously hit the network whenever we need a random value.

Now you're talking. Hit Google with a random query and hash the results html page. This should give you a truly random number.

silent d:

To generate a random hash, just hash the string "random"

donniel:

TheRider:

Bernie:

Cloud computing sounds random to me; we should obviously hit the network whenever we need a random value.

Now you're talking. Hit Google with a random query and hash the results html page. This should give you a truly random number.

Where do you get the query from? Obviously it has to be a dictionary word, since nonsense will always fetch the same result page (No results found).

Then you'll have to account for events like network or service outages...

...Or maybe you were kidding...

donniel:

TheRider:

Bernie:

Cloud computing sounds random to me; we should obviously hit the network whenever we need a random value.

Now you're talking. Hit Google with a random query and hash the results html page. This should give you a truly random number.

Where do you get the query from? Obviously it has to be a dictionary word, since nonsense will always fetch the same result page (No results found).

Then you'll have to account for events like network or service outages...

...Or maybe you were kidding...

// Initialize randomizer
// This really doesn't have enough entropy....
// Get the val

bnt:

There were some well-publicised problems with random-number generators in the past - e.g. this - but I hardly think this is the answer..! If your compiler's rand() function doesn't generate sufficiently-random numbers, get a better compiler.