older DEMO program

Sam Rawlins sam.rawlins at gmail.com
Wed Nov 2 01:21:48 CET 2011

Hi Bill,

My recommendation would be to use a higher-level language with GMP
bindings. For example, in Ruby:

sam at ubuntu6510:~$ irb -r gmp
>> two = GMP::Z(2)
=> 2
>> two**126 - 1
=> 85070591730234615865843651857942052863

Or an online service like Sage Online (http://www.sagenb.org/).

However, neither of these will be happy to compute your modulus (
2^(2^127-1)-1 ) since they both use GMP for integer exponentiation, which
doesn't compute 2^n for n bigger than an unsigned long int:

On Tue, Nov 1, 2011 at 12:26 AM, Bill Bouris <leavemsg1 at yahoo.com> wrote:

> Dear Sir,
> I remember using an older DEMO program on your site
> that performed calculations on large numbers. It was the
> original DEMO calculator instead of the new PI calculator.
> Is that DEMO still accessible online ?? somewhere ???
> Bill Bouris
> I want to compute 2^(2^(2^126-1)-1) mod 2^(2^127-1)-1,
> or a primality test on C5. It did such huge calculations using a
> modular technique without creating the big numbers themselves.
> If this calculation is equal to +1 (OR) (2^(2^127-1)-2, then
> C5 is prime! according to (my) Riesel's Theorem. Only one
> calulation is needed. Can you help me???
> _______________________________________________
> gmp-discuss mailing list
> gmp-discuss at gmplib.org
> https://gmplib.org/mailman/listinfo/gmp-discuss

Sam Rawlins

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