Ciao, Il Ven, 27 Aprile 2018 2:46 pm, Marc Glisse ha scritto: > On Fri, 27 Apr 2018, Niels Möller wrote: >> Marc Glisse <marc.gli...@inria.fr> writes: >>> There would be a significant advantage to mpq if we could have a >>> non-allocated 1 for the denominator. But indeed, with the current code >> >> We could do that internally, even if we don't advertise it for other gmp >> users. > > We document that users can use the denominator of a mpq_t as a regular > mpz_t and apply pretty much any mpz_t operation to it. So it seems hard to > handle just that case internally.
I agree, mpq_denref(Q) should work as a generic mpz_t. That's why I also pushed the "Support lazy mpq_t also in the denominator" patch. >> We could have a single mpq object representing 0/1 with _mp_alloc == 0 >> for both parts, and initialize with struct assignment or memcpy. >> >> We would just ensure that mpz realloc keeps supporting thuis case. ... and it's not just a problem of supporting mpq_denref() we should also change some mpq_ functions. If someone does init an mpq_t with: mpz_init (mpq_numref (accumulator)); mpz_roinit_n (mpq_denref (accumulator), &const_one, 1); then a simple, mpq_add (accumulator, accumulator, another_mpq) might fail. Niels is right when he says we should not mention on the manual that sometimes writing on a read-only mpz does actually work. It does not work as a general rule and it may not be supported by future releases, that's the only information we can document. Ĝis, m -- http://bodrato.it/papers/ _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org https://gmplib.org/mailman/listinfo/gmp-devel
