Re: [ublas] Matrix decompositions.

Subject: Re: [ublas] Matrix decompositions.
From: Salman Javaid (javaid.salman_at_[hidden])
Date: 2013-05-15 22:12:06

Thank you, Oswin for the detailed response. I am going to update the code.

David, Nasos, any advise on coding conventions? Or anything else that you
can possible suggest? I will stand grateful.

Best Regards,
Salman Javaid

On Tue, May 14, 2013 at 10:53 PM, oswin krause <
oswin.krause_at_[hidden]> wrote:

>  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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