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Date: Wed, 22 Dec 2021 09:27:56 -0800 (PST)
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Subject: Re: Ada.Numerics.Big_Numbers.Big_Integer has a limit of 300 digits?
From: Michael Ferguson <michaelblakeferguson@gmail.com>
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On Wednesday, December 22, 2021 at 11:02:03 AM UTC-6, Luke A. Guest wrote:
> On 22/12/2021 05:57, Michael Ferguson wrote: 
> > I just started using the Big_Integer library that is a part of the 202X version of ADA. 
> > 
> > It is repeatedly described as an "arbitrary precision library" that has user defined implementation. 
> > 
> > I was under the impression that this library would be able to infinitely calculate numbers of any length, but there is clearly a default limit of 300 digits.
> What are you doing that requires that number of digits?

I am working on ProjectEuler.net problem number 48.

The questions asks you to sum the numbers n^n for (2 <= n <= 1000) and determine what the last ten digits of this number are.

Obviously, this is quite a trivial problem when using any arbitrary precision library.

I had incorrectly determined that 700^700 had 300 digits, in fact 700^700 = 3.7E1991.

However, my code strictly breaks when the loop range is set to 683, which 683^683 = 8.12E1935.

So, that is interesting that the Big_Integer type works numbers of just under 2000 digit length despite Bignum_Limit : constant := 200.