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Re: [microsound] random numbers WAS:oval armani



brad,

----Original Message Follows----
From: { brad brace } <bbrace@xxxxxxxxxx>

I'm often wondering about the 'random-number' feature in
applications: how does one program _randomness? Is there
really such a thing?


if you want a technical answer, and not a rhetorical one:

"How does acomputer, which is designed to store and process numbers accurately and reproducably, obtain seemingly unpredictable random numbers? One way is to sample an external random process such as thermal noise, but this requires additional hardware. A less expensive and more commonly used approach is to employ an algorithm called a pseudo-random number generator which produces a sequence of numbers that satisfy most of the criteria for randomness, with the notable exception that the sequence repeats itself. It is possible to make the period of the sequence so long that for most purposes it can be considered random... pseudo random number generators generally use the most recently generated random number for calculating the next. As a result, most algorithms give the user the option of specifying a 'seed' value...starting from the same 'seed' value will always yield the same sequence of random numbers. That means that two different computer runs...can always be made to have exactly the same results."

(Computer Music, Charles Dodge and Thomas A. Jerse, 1985)

kind of defeats the purpose, don't you think?

best,
derek


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