On Tue, Jan 8, 2013 at 12:28 AM, Torbjorn Granlund <t...@gmplib.org> wrote: > ni...@lysator.liu.se (Niels Möller) writes: > > Hmm. I guess one could go down to only 8 bits or so for the alloc field, > and for larger allocations, store the number of allocated limbs at the > head of the limb array (in the case limb size is not artificially small, > it could be just _mp_d[-1]). > > That's another idea. > > Do you think 48 bits (or 47 bits absolute value) for _mp_size will be > large enough for the foreseeable future (say, 10 years)? > > I think that will be sufficient for some hundred years, since any > super-linear algorithm applied to an operand of 2^53 bits (2^47 64-bit > limbs) would hardly ever terminate even with a multi-THz CPU.
Well, pi has been computed to 10 trillion digits, which is 2^45 bits. Extrapolating the records from the last 60 years, a 2^53-bit multiplication can be expected to occur within 30 years, though certainly with highly parallel hardware, not a single CPU. Actually, NTTs of that size ought to be feasible on the current generation of top supercomputers, in theory at least. Of course 10+ years from now you could just release GMP 7 and break backwards compatibility again ;-) Fredrik _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org http://gmplib.org/mailman/listinfo/gmp-devel
