Re: Matrix decompositions.

Hi,

in the order I stumbled over the things:

main.cpp
line 44-54: you don't need a copy, instead you should use a combination 
of row/subrange.
line 58-60: you should take a look at inner_prod
line 63: 0.00025 is too big.
line 66: You should never create H explicitly.
line 67: because you formed H, this step is O(n^3) which makes the whole 
algorithm O(n^4). This can be done in O(n^2)
line 73-79: same applies here.

Greetings,
Oswin
On 14.05.2013 22:12, Salman Javaid wrote:
> Hello uBLAS Contributors:
>
>                                      I have applied to GSoC 2013 and 
> pitched implementation of SVD factorization for uBLAS. In order to 
> better prepare myself and to get my hands dirty at uBLAS, I ended up 
> implementing QR Factorization employing Householder Reflections using 
> uBLAS. This is only the first draft and will be needing significant 
> improvement, e.g., computation of QR decomposition of 100 * 100 matrix 
> takes around 30 seconds. But I guess just to get familiar with code 
> base, it was a good exercise. Over the next week or two I will be 
> trying to optimize the code.
>
>
>                                      I will be absolutely grateful if 
> contributors can have a quick glance at the code, and point me to any 
> improvements they can suggest. Particularly in speeding up matrix 
> multiplication.
>
> I used Visual Studio 2010 to compile the code. I will try to get the 
> code running on my Ubuntu machine in a couple of days hopefully.
>
> Here the header file: 
> https://github.com/salmanjavaid/QR_Decomposition/blob/master/QR_Header.hpp
>
>
> The main file: 
> https://github.com/salmanjavaid/QR_Decomposition/blob/master/Main.cpp
>
>
> Best Regards,
> Salman Javaid
>
>
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