[ExI] isaac's number

spike spike66 at att.net
Thu Aug 3 02:28:43 UTC 2017



From: extropy-chat [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of John Clark
Subject: Re: [ExI] isaac's number


On Wed, Aug 2, 2017 at 12:04 PM, spike <spike66 at att.net <mailto:spike66 at att.net> > wrote:


​> ​>…I don’t know John.  I need to learn up on this, figure out how the rand() function works in VBA. 



>…You got me curious so I looked it up, it's 32 bit pseudorandom


Generator is called called "MT19937"…


Cool thanks for that.



>… super long period of 2^19937 -1 (a Mersenne prime)…


That comment was worth the price of admission.  I recall hearing of the discovery of that Mersenne prime, way back when I was in fifth grade.  I was just then learning about Mersenne primes.  It made the Scholastic News for breaking the record for the largest known prime number.  I was in college before that record was broken.


… ​


>…through even a simple hash function will​ greatly improve it, although of course that would also slow things down.  John K Clark​


I have used the Excel VBA random function since macros first appeared, which was in 1993.  That too brings back fond memories, for I recall hearing that a new embedded language was coming with the new Excel 5.0, which was much more practical than the previous macro code.  If you were a geek back in those days, you may recall before 1993, instruction sets resided in a worksheet.  The code didn’t care if you modified that sheet.  So you could write self-modifying code.  That was kinda cool for some applications, but it made for extremely brittle code that could run perfectly for months, then suddenly  stop working, and the programmer could never figure out what broke on it, regardless of how geeky he was.


I wrote and ran a ton of Monte Carlo sims in those days.  One of them was a rocket ascent program which I think Keith Henson still has and might still use.




Things got better.  They got waaaay better.





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