fixed size integer arithmetic
Richard B. Kreckel
kreckel at ginac.de
Mon Sep 3 00:02:18 CEST 2007
I suppose you guys are talking about modular arithmetic, right?
Evan Lavelle wrote:
> point14 at magma.ca wrote:
>> Hello,
>>
>> Is it possible in GMP to have the size of integers (like mpz_t) to be
>> fixed in size and invariant (eg, a fixed number of bits) as well as being
>> arbitrarily large?
>>
>> I mean once it's declared or initialized to be of a certain size, the size
>> no longer changes, and arithmetic operations (add, mul, etc) that would
>> normaly grow the number would simply cause it to roll over.
>>
>> Is this possible with GMP and if not, do you have suggestions?
>
> I looked at this some time ago, and went through maybe 6 different
> libraries to get this functionality, and looked in some detail at ltm
> and gmp. My conclusion - possibly incorrect - is that there's nothing
> obvious out there which does this for you.
Did you try CLN <http://www.ginac.de/CLN/>? CLN is not C, though. It is C++.
(I may mention that in CLN the modulus (called "invariant" above) is a
dynamic attribute of the class, not determined at compile time. IOW:
different moduli are not different C++ types and mismatches cause
runtime errors.)
-richy.
--
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>
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