Please excuse typos; composed on a handheld device. -----Original Message----- From: "Linda Alvord" <[email protected]> Sender: [email protected] Date: Sat, 29 Oct 2011 12:05:37 To: 'Programming forum'<[email protected]> Reply-To: Programming forum <[email protected]> Subject: Re: [Jprogramming] 32- & 64-bit PRNGs
Also I forgot that "pi times" is O. ]oh=: 13 : '-^o.*0j1' 1j_1.2246467991473532e_16"_ ]my=: 13 :'^1p1*0j1' _1j1.2246467991473532e_16"_ Even more convincing. Linda -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Linda Alvord Sent: Saturday, October 29, 2011 11:49 AM To: 'Programming forum' Subject: Re: [Jprogramming] 32- & 64-bit PRNGs Here's what I was thinking: -^1p1*0j1 1j_1.22465e_16 I forgot that "i" is 0j1 (quite a coincidence?) in J Also, it was always more satisfying to me that the result is 1. However, we do agree. -^1p1*0j1 1j_1.22465e_16 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roger Hui Sent: Friday, October 28, 2011 11:48 AM To: Programming forum Subject: Re: [Jprogramming] 32- & 64-bit PRNGs Isn't that just saying that (^1)^0 is 1? On the other hand: _1 = ^ 1p1 * 0j1 1 http://www.jsoftware.com/jwiki/Essays/Euler%27s%20Identity On Fri, Oct 28, 2011 at 12:48 AM, Linda Alvord <[email protected]> wrote: > Ken might have answered that God must be an awesome mathematician, since he > might have understood God better than most. > > (^1)^-o.i.1 > 1 > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Ian Clark > Sent: Thursday, October 27, 2011 2:38 PM > To: Programming forum > Subject: Re: [Jprogramming] 32- & 64-bit PRNGs > > I wonder if Carl Sagan, like Feynman, wasn't having joke after joke at > his audience's expense? (APWJ p 136, see also end of: > http://www.jsoftware.com/jwiki/Doc/Articles/Play151) > > The probability of any given finite pattern turning up in the first N > digits of a random sequence tends to 1 as N tends to infinity. The > aforementioned site estimates the odds for various values of N: > http://www.angio.net/pi/piquery#likely > > Sagan didn't say how many digits Ellie had to search (N) for her > (initially undefined) pattern. Was N sufficiently low to reject the > null hypothesis? The implication is: it wasn't. Nor is pi a random > series (it's pseudo-random). And when you're reading the Mind of God > -- does the null hypothesis have any cause to exist? -- viz is there > any merit in *guessing* the Mind of God? > > Nor is it the first time in the novel Ellie is the victim of illusion > (the alien deludes her he's her father... and yet she knows that). > > The whole novel is shot through with existential jokes, playing-off > science against sentiment. Once I spotted that I was ready to forgive > Sagan any amount of Slartibartfastian pseudo-engineering of pi. > > > On Thu, Oct 27, 2011 at 1:51 PM, Roger Hui <[email protected]> wrote: >>> For initial experiments, there's already a site which stores the first >>> 200M digits of pi, for hobbyists wanting to do Carl Sagan >>> "Contact"-type research: >> >> When I first read that in "Contact" years ago it knocked down by >> several notches my respect for the novel. Even the Almighty doesn't >> have any choice about the digits of π, right? What's He/She going to >> do about the various power series, f'instance? >> >> >> >> On Thu, Oct 27, 2011 at 5:26 AM, Ian Clark <[email protected]> wrote: >>> Being old enough to have learned my electronics before the digital >>> age, I wonder if it isn't time to reconsider shot noise as a source of >>> random numbers. It has a forensic advantage in lottery draws, and >>> monte-carlo simulations of fraught political topics like climate >>> change, by taking the "pseudo" out of "pseudo-random". >>> >>> For years the UK gov ran a device called ERNIE >>> http://en.wikipedia.org/wiki/ERNIE#ERNIE >>> to pick premium bonds (a savings scheme where the interest payable was >>> put in a monthly draw). >>> >>> A device to generate binary digits from electronic noise would be so >>> simple it ought to be fitted as standard to today's desktop computers. >>> Failing that, if I had a serious need for true random numbers I'd >>> experiment with an open microphone line using Audacity to save the >>> number stream as a WAV. >>> >>> Need a reproducible number stream? With the amount of free storage >>> space in the "cloud" (I currently have access to around 2 GB and I >>> don't remember asking for it) why not just store it? I also have a 1TB >>> disk drive, mostly lying empty. >>> >>> For initial experiments, there's already a site which stores the first >>> 200M digits of pi, for hobbyists wanting to do Carl Sagan >>> "Contact"-type research: >>> http://www.angio.net/pi/piquery >>> Aside: ought the hunt for meaningful sequences in pi to be called >>> perimancy? :-) >>> >>> >>> >>> On Fri, Oct 14, 2011 at 8:30 PM, Zsbán Ambrus <[email protected]> wrote: >>>> On Fri, Oct 14, 2011 at 2:33 PM, Zsbán Ambrus <[email protected]> wrote: >>>>> On Fri, Oct 14, 2011 at 1:08 PM, Ewart Shaw <[email protected]> wrote: >>>>>> I want to generate pseudorandom sequences that are the same for 32- & >>>>>> 64-bit J. >>>>> >>>>> Have you tried the other random generators the (9!:43) foreign makes >>>>> available? I'd guess some of them are the same for 32 and 64 bit J. >>>> >>>> Hmm, from a quick test, it seems Roger is right: none of the built in >>>> generators give the same results on the 32-bit and 64-bit J. >>>> >>>> Let's use the random generation functions from GSL ( >>>> http://www.gnu.org/software/gsl/ ) then. This example implements >>>> roll, but not deal. >>>> >>>> >>>> $ cat rngwrap.c >>>> #include <gsl/gsl_rng.h> >>>> >>>> /* >>>> Allocate a new random generator of the Mersenne Twister algorithm >>>> and initialize it with the default seed. >>>> */ >>>> gsl_rng * >>>> wrap_newrng(void) { >>>> gsl_rng *g = gsl_rng_alloc(gsl_rng_mt19937); >>>> return g; >>>> } >>>> >>>> $ cat rngwrap.ijs >>>> NB. random generator functions from GSL >>>> rngobj=: <'./rngwrap.so wrap_newrng > x'15!:0$0 >>>> rollint=: './rngwrap.so gsl_rng_uniform_int > x *c x'15!:0 rngobj;] >>>> rollflo=: './rngwrap.so gsl_rng_uniform_pos > d *c'15!:0 (,<rngobj)"_ >>>> roll=: rollflo`rollint`[:@.*"0 :[: >>>> >>>> $ gcc -Wall -O -fpic -lm -lgslcblas -lgsl -shared -o rngwrap.so rngwrap.c >>>> $ jconsole rngwrap.ijs >>>> roll (10$1e4),5$0 >>>> 9997 1629 2826 9472 2316 4849 9574 7443 5400 7399 0.759944 0.658637 >>>> 0.315638 0.804403 0.519672 >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
