[isabelle-dev] Proper sign of gcd / lcm on type int

Makarius makarius at sketis.net
Fri Jun 3 21:29:54 CEST 2016

On 03/06/16 18:49, David Matthews wrote:

> The Poly/ML implementation was based on the idea that something called a
> "multiple" ought to follow the usual rules of multiplication; nothing
> stronger than that.  I don't think I found anything that indicated what
> the sign should be.  The GCD code uses GMP's GCD if possible; the LCM
> code is just derived from that.
> I have no strong opinions on this and I'm happy to change it.  There's
> also the question of whether to add it to the IntInf structure and
> signature despite the incompatibility with the "official" library
> definition.

How is the situation wrt. planned updates of the SML Basic Library

Maybe this is a chance to add IntInf.gcd and IntInf.lcm officially,
which a clear specification about the sign, whatever that might be.


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