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From: Andy Little (andy_at_[hidden])
Date: 2005-10-21 05:55:52

"Phil Richards" wrote

> I certainly don't disagree with that statement. But I only really have
> experience of dimensions and units that are compatible with the SI
> view of things, so it is practically impossible to design a library to
> support other modes without knowing more about how they operate...
> (That, I suspect, is true for all the people who've tried over the last
> couple of years.)

Not sure if youre include me in that. I believe that pqs is a great solution
for SI quantities. The primary purpose of a physical quantity library is to
cater for common practise, rather than being some sort of tool kit for ad-hoc
unit systems to be created. Defining a unit system is a non-trivial task. The
dimensional analysis part is trivial really. The difficult part is output and to
be honest I havent seen a library apart form pqs that tackles this well. Output
is messy even in the SI. I believe that users ( including myself) want
simplicity. I dont want to have to spend time creating output facilities or
making complex typedefs for commonly used SI quantities. The design of an SI
quantity library is possible because they have published detailed definitions of
their base units and the output format. pqs doesnt preclude anyone using the
library for their own system, writing their own unit conversions and their own
output format. but obviously it cant do that for them, unless some detailed
definition of what these systems are is provided. Even then is there a common
requirement there?

Andy Little

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