Information on calculator Random Number Generators from PPC Journal articles

[Dieter]

(11-15-2016 09:32 PM)Paul Dale Wrote:  You didn't include the \( frac ( 2^{20} x_n ) \) part. The leading bits don't pass the randomness tests but going down the mantissa a bit does.

Sorry, it was not clear to me that R_n is returned and not x_n. Adding the 20-bit shift improves the results very much, if (!) the algorithm runs in a regular binary double precision environment with 53 bit mantissa. On the other hand the method may not be the first choice on a standard 10-digit BCD calculator: here only three digits may remain in the fractional part after the multiplication by 2^20. I tried shifting by 13 bits, i.e. x_n*8192, which yields 2..3 more digits, but here other problems arise.

Dieter