[Coco] Is the RND command really generating a random number?

[John Guin]

Did anyone ever try to figure out how "long" the list of numbers was before it started repeating?

There is probably an analytic way of doing this based on the algorithm being used, but I can't help but wonder if rounding errors might skew the results.

John

-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Arthur Flexser
Sent: Friday, May 19, 2017 9:13 AM
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Subject: Re: [Coco] Is the RND command really generating a random number?

RND(TIMER) will just give a random number between 0 and whatever the current value of TIMER is.  RND with a negative argument will reseed the random number generator, starting the upcoming sequence of random numbers in a different place than where it would ordinarily start.  RND(-TIMER) makes the seed dependent on the TIMER value, so you'd get a different sequence of pseudo-random numbers each time you run the program.
RND(TIMER) will only affect the scaling of the current random number to make it within the required interval, but won't affect the underlying sequence of numbers generated.

Art

On Fri, May 19, 2017 at 11:10 AM, Salvador Garcia via Coco < coco at maltedmedia.com> wrote:

> Why won't RND(TIMER) work?
>
> Thanks, Salvador
>
>       From: Arthur Flexser <flexser at fiu.edu>
>  To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
>  Sent: Thursday, May 18, 2017 11:26 PM
>  Subject: Re: [Coco] Is the RND command really generating a random number?
>
> RND(TIMER) will not work for seeding the random number generator.  It 
> has to be RND(-TIMER) with a minus sign.
>
> Art
>
> On Thu, May 18, 2017 at 10:52 PM, Bruce W. Calkins < 
> brucewcalkins at charter.net> wrote:
>
> > Short answer: No.
> >
> > Longer answer: RND calls some sort of psudo-random lookup table. If 
> > you enter the table at the same point you will get the same sequence out.
> You
> > need to "randomize" the entry point.  As someone mentioned one 
> > method is
> to
> > add the command RND(timer) Which calls the current timer value, 
> > which is generally different each time, one is hard pressed to turn 
> > on their CoCo, load a program and run it in the same time repeatedly.
> >
> > Bruce W.
> >
> >
> >
> >
> > On 05/18/2017 08:39 PM, Rietveld Rietveld wrote:
> >
> >> I used the RND command to generate a random game play option in the 
> >> cocoflash, but it doesn't seem to be very random. Some titles come 
> >> up
> more
> >> than the laws of probability would suggest is possible.  instead I 
> >> am
> now
> >> using a small math equation that uses a PEEK of the clock value.  
> >> This
> has
> >> resulted in a far more random looking selection
> >>
> >> Sent from my BlackBerry 10 smartphone.
> >>
> >>
> >
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> >
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