# Re: [Q] Can a good random bit sequence generator be a good random number sequence generator?

*From*: "David A. Heiser" <daheiser@xxxxxxx>*Date*: Sun, 9 Apr 2006 21:06:28 -0700

<sjtu.0992@xxxxxxxxx> wrote in message

news:1144467472.471117.12360@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hi,+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I am looking for the comments or any references (books or papers)

regarding the subject title.

Thanks,

Albert

You have to look at the issue from a computer and programming view point.

If the bit sequence file from the generator say passes Diehard 3, then we

can assume that it has acceptable random bit sequences. There are several of

the Diehard tests that stress this characteristic. You can go to more severe

testing using L'Ecuyer's tests to assure this characteristic.

I have no idea if the mersine twister will pass L'Ecuyer's tests. It is

really is an old generator.

If 32 bit sequential segments of the sequence are cut out and taken as an

unsigned long integer, then we have a good random number sequence, between

2^32 and 0. If we convert to a signed long integer, the numbers are now

positive and negative, and the limits of the numbers as a uniform

distribution are 2^31 to -2^31-1. We still have a uniform distribution.

If however 64 bit sequences are taken and taken as a double precision

floating point number, then we have totally lost the two critical aspects, a

uniform distribution between a lower and upper limit and a random

characteristic of the number in a decimal sense. A double precision floating

point number really has 65 bits, where the extra bit is a hidden bit,

assigned a value of 1, and the 52 bit mantissa shifted left to assure that

the hidden bit is one.

David Heiser

.

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