Re: Factorials on the 86


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Re: Factorials on the 86



Since the issue of memory has come up, both the 85 and 86 I used to do
this have between 1k and 2k free.  Also, the 86 (with about 1k-2k free)
is faster than an almost empty 82 doing 69!

Todd

Jeff Tyrrill wrote:
>
> This would not make a difference on a calculator. Memory does not
> "magically" speed up a processor. The only reason it makes a difference on
> a PC is because a PC swaps memory on the hard disk so it can simulate more
> memory than it actually has, and most PC environments need more than 32MB
> of memory.
>
> And in case anybody would point out that a TI-85 or TI-86 runs slower
> (overall) when it has less memory free, I will point out that it is not the
> free memory that speeds up the calculator, but the used memory that slows
> down the calculator, because it takes longer to search for a specific
> variable or store to a variable.
>
> The factorial function on the TI-86 probably has a smart algorithm so it
> doesn't have to internally multiply 449 numbers, while the TI-85 just does
> it the slow way.
> ________________
>
> Jeff Tyrrill
> http://tyrrill-ticalc.home.ml.org/
> http://ti-philes.home.ml.org/
>
> -----Original Message-----
> From:   Williams, Matt [SMTP:Williams.Matt@CON-WAY.COM]
> Sent:   Tuesday, February 17, 1998 11:42 AM
> To:     CALC-TI@LISTS.PPP.TI.COM
> Subject:        Re: Factorials on the 86
>
> It's kind of like having a computer with 32MB of RAM vs a computer with
> 128MB of RAM trying to run something.  The amount of memory available on
> the calculator has a high correlation to the speed of the calculator.
> Just for kicks, try a TI-85 with nothing on it vs a TI-86 that is
> completely full and see which one is faster.
> --
>
>         -iceboxman
> TI-CALC Discoveries
> http://ticd.home.ml.org
> or
> http://www.geocities.com/SiliconValley/Peaks/4152/index.html
>
> iceboxman@geocities.com
>
> >----------
> >From:  Todd Stanley[SMTP:toddestan@AOL.COM]
> >Reply To:      Todd Stanley
> >Sent:  Friday, February 13, 1998 1:33 PM
> >To:    CALC-TI@LISTS.PPP.TI.COM
> >Subject:       Factorials on the 86
> >
> >A few days ago I was fooling around with my 86's factorial function in
> >math class, when I found that putting numbers that weren't integers
> >didn't cause an error like on my 85 or my friend's 82.  For example,
> >10.5! spits out 11899423.084 instead of ERROR 04 DOMAIN.  I read in the
> >manual (pg. 294) that the calculator uses the "Gamma" function to
> >evaluate non-integers when doing factorials.  My math teacher had no
> >clue what the manual is talking about and what the gamma function is.
> >What is the Gamma function and what does it do (as in what does the
> >number it give out mean)?
> >
> >Also, I noticed that the 86 is very much faster when evaluating
> >factorials than the older 85.  If you have an 85 and an 86, try
> >evaluating 449! at the same time on both calculators.  The 86 gives back
> >an answer almost instantly, while the 85 takes a few seconds.  Does the
> >86 use a different way to computer factorials?
> >
> >Todd
> >


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