How many double numbers are there between 0.0 and 1.0?

Posted by polygenelubricants on Stack Overflow See other posts from Stack Overflow or by polygenelubricants
Published on 2010-06-05T02:51:23Z Indexed on 2010/06/05 7:22 UTC
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random

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floating-point

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double

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precision

This is something that's been on my mind for years, but I never took the time to ask before.

Many (pseudo) random number generators generate a random number between 0.0 and 1.0. Mathematically there are infinite numbers in this range, but double is a floating point number, and therefore has a finite precision.

So the questions are:

Just how many double numbers are there between 0.0 and 1.0?
Are there just as many numbers between 1 and 2? Between 100 and 101? Between 10^100 and 10^100+1?

Note: if it makes a difference, I'm interested in Java's definition of double in particular.

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