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Re: Calculating Pi [message #53328 is a reply to message #53253]

Tue, 03 April 2007 00:44

Paolo Grigis
Messages: 171
Registered: December 2003

Senior Member

jschwab@gmail.com wrote:
> On Apr 2, 4:09 am, Paolo Grigis <pgri...@astro.phys.ethz.ch> wrote:
>> The problem here is not one of method for computing Pi
>> (as remarked, plenty are available), but rather the lack
>> of an arbitrary precision library in IDL... (or has
>> anybody already written one?)
>>
>> Ciao,
>> Paolo
>
> There are a class of formulas called Bailey-Borwein-Plouffe (BBP) that
> let you find the nth digit, without having found the preceding ones.
> If you head to your library or Google around, I'm sure you can find
> out enough to show off to your heart's content. With double precision,
> I think that should let you get the first 10^7 digits or so.
>
> I Googled and found code examples here
> http://crd.lbl.gov/~dhbailey/expmath/bbp-codes/
>
> Cheers,
> Josiah

Yes, but these are hexadecimal digits, which you still have
to convert into decimal form... so you still need at least
one routine from the arbitrary precision library.

Ciao,
Paolo

>

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		Calculating Pi By: Braedley on Sun, 01 April 2007 10:07
		Re: Calculating Pi By: Paolo Grigis on Tue, 03 April 2007 00:44
		Re: Calculating Pi By: JD Smith on Mon, 02 April 2007 15:04

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