[Numpy-discussion] ufuncs on user-defined types in numarray

[Gary Ruben]

First, thanks Todd for elevating this to 'requested feature' status.

Konrad, I had no idea what interval arithmetic is, so I looked it up. I'm not sure if what I've done is considered interval arithmetic - I suspect it is, but that I've only implemented it partially. The code isn't that clever. It doesn't care about propagating rounding errors correctly at the error limits.
It just implements a brute-force approach to calculating operations on the error limits of a data-point value along with the central value. This is already more accurate than what most people do, which is to linearise the error limits and treat them as infinitessimals.
The central and outer values are grouped in an object and any operations are applied, without any consideration of rounding errors, to all three values for every operation.

Gary

----- Original Message -----

> > I didn't realise this was possible. I should use it on my 
> > ErrorVal module <http://users.bigpond.net.au/gazzar/python.html>. 
> > Last time I tried (quite a
> 
> Indeed! You could then even have arrays of ErrorVal objects with no 
> extra effort, at least as long as ErrorVal doesn't implement the 
> sequence protocol (because then all the Numeric functions will 
> silently convert them to arrays).
> 
> Your module looks interesting. What does it do internally, interval 
> arithmetic?
> 
> Konrad.

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