on Tue Jan 31 2012, Daryle Walker
From: John Date: Tue, 31 Jan 2012 16:28:41 +0000
Modulo: NO
Integer types that are bounded (fixed precision) and implement modular arithmetic (ie built-in integers on most/all platforms) can and should set is_modulo field to true.
Yes, but that's not what I'm talking about. The built-in integers model a subset of real numbers, and the modulo properties (if present on the hardware) are a side-effect of the wrap-around mechanic. This isn't the case with an intentional modulo type (with arbitrary modulus). For instance, if we have a modulo-5 UDT, then the value "1" represents not just 1, but any integer that can be expressed as 5x + 1. Since the state represents a whole class of numbers, it doesn't model to real numbers any more than a polynomial type does.
I think that's a valid, but pretty twisted, way to look at it. An instance of a modulo-5 UDT only represents a whole class of numbers if that's dictated by the way it's being used. It's no more intrinsically a representative of a class than it is an individual. -- Dave Abrahams BoostPro Computing http://www.boostpro.com