Two questions about mpz_addmul() and mpz_submul()
tege at swox.com
Mon Sep 20 16:53:30 CEST 2004
Roberto Bagnara <bagnara at cs.unipr.it> writes:
I have just come across these functions and I have
1) Can I assume that mpz_addmul and mpz_submul
are not less efficient than what a user could write
using other GMP mpz_* functions? I am especially
concerned about the cost of allocation and deallocation
of space to hold the result of the multiplication.
It is probably possible to find some corner cases where they are
a tad bit slower, but since mpz_addmul is implemented on top of
mpn, there shouldn't be extra overhead compared to separate
The main reason for mpz_addmul is to reach the optimized
mpn_addmul_1 and mpn_submul_1.
2) Is there some fundamental reason why these functions
are not available for rationals?
We keep mpq small, but sinze mpz functions can be applied to mpq
numerators and denominators, mpq's lack of a complete set of
functions should not be a big problem.
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