[SciPy-user] Units in SciPy

Peter Wang pwang at enthought.com
Wed Mar 30 17:13:03 CST 2005


Duncan Child wrote:
> One potential issue is that a units package has to guess whether the 
> user wants to convert a temperature gradient or a temperature:
---snip---
> 3) does anyone have input or suggestions regarding the temperature issue?

One thing I'd like to point out is that this is not specific to temperature. 
Whenever two unit systems have different origins, the unit framework will have 
to distinguish between differences and positions.  (Alternatively, the 
framework can handle all positional measurements as (X - X_0), and use one 
general-case transformation.)

In general, operators are not unit preserving; it's just that we intuitively 
expect addition/subtraction to be better behaved than multiplication.

Off the top of my head, time measurement also suffers this problem.  I'm sure 
there are others (although they're probably obscure).

-Peter



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