CODEWITHSUNDEEP
performancegmp
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rwst

Reputation: 2675

Does gmp lazy canonicalization with mpq_t?

With gmp rationals, do I have the duty to bookkeep my calls to canonicalize() (which can be costly performance-wise)? Does gmp know that the rational was not changed since the last call to canonicalize() and will just return if I attempt canonicalization?

I cannot find an answer in the documentation, and maybe someone already looked into the source for this.

Upvotes: 0

Views: 130

Answers (1)

Grzegorz Szpetkowski
Grzegorz Szpetkowski

Reputation: 37934

It won't likely just return, as mpq_t does not contain any form of information whether fraction is already in canonical form or not. At least GMP documentation does not mention it as of 16.2 Rational Internals:

mpq_t variables represent rationals using an mpz_t numerator and denominator (see Integer Internals).

In practice, it will likely call mpz_gcd() (or equivalent), to check whether numerator and denominator are coprimes or not.

Upvotes: 0

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