"Paul A Bristow" wrote [...]
And being MATH constants, they haven't changed ;-))
(Unlike some of the physical constants - which is why I would strongly recommend keeping them apart, for example, by being in different namespaces).
Physics constants are usually dimensionful physical quantities so it makes sense to put them in the namespace of the quantity library as you would need its machinery. I put math constants in pqs sub-namespace for simplicity as I need these ( at least while waiting for boost::math::constants), but Its not my intent to submit a boost math constants library. Because physics constants are wrapped in a struct named to identify the particular constant (or family) there shouldnt be a problem within the quantities library and the math and physics sub namespaces are redundant ( which has been expressed to me privately and I agree with FWIW) The quantities constants header is pretty self-contained so a user can alternatively choose boost::math::constants if they prefer. regards Andy Little