Re: comments on Matrix

2013/3/20 Rik Cabanier <cabanier@gmail.com>
>
> and hearing that some of these mistakes are copied from other,
>> already-blessed Web APIs is even more discomforting.
>>
>
> What you call a mistake (QR decomposition) is a well documented, fast
> alternative (I know at least 3 now that use this).
> From the paper you quoted:
>
> Also, the algorithms for QR are simple and efficient. The drawback is that
> the orthogonal matrix
> extracted is not particularly meaningful: it is not independent of the
> coordinate basis used, and so has no
> “physical” significance
>
>
> This implies that the QR algorithm is fast but it doesn't produce results
> that you should use directly.
> So, we should use it for matrix interpolation but not to get the
> decomposed values out.
>

That's not what I get from this quote. This is saying that QR decomposition
is simple and efficient to perform, but is not going to give good results
for matrix interpolation, since that should definitely be
coordinate-independent and "physically meaningful".

Benoit