[PPL-devel] Re: C++ interface and mpz_addmul

[Kevin Ryde]

Roberto Bagnara <bagnara at cs.unipr.it> writes:
>
> it seems that C++ statements of the form
>
>      a += b*c
>
> for a, b and c of type mpz_class, are not translated
> by the C++ interface into an invocation of mpz_addmul.

Alas you're right.  mpz_addmul is only used for "mpq += mpz" at the
moment.  (Hmm.  Should use mpz_addmul_ui for "mpq += ulong" too I
guess.)

> The reason I am asking is twofold: on the one hand, expressions
> like that are quite common in several applications and they usually
> occur in critical computation paths (e.g., applications computing
> zillions of scalar products);

You can call mpz_addmul directly with mpz_class::get_mpz_t if you
want.  Not terribly pretty, but it'll work right now.

> on the other hand, the template machinery
> used to implement the C++ interface of GMP would seem powerful enough
> to do the right thing.

I wonder if the templating can cope with two operators like that.

> Am I missing something?
> If not, are there any plans to enhance the C++ interface so as to
> capture this case?

Gerardo?