Subject: Help with very very slow determinant calcuation
From: Nghia Ho
Date: Sat, 6 Aug 2011 18:23:40 -0700 (PDT)
Can you elaborate more on how factorizing the matrix can help? My background isn't in mathematics, I only did basic engineering level maths.
>________________________________
>From: Claudio Delpino <cladelpino at gmail.com>
>To: Bernard Hurley <bernard at marcade.biz>
>Cc: Nghia Ho <nghiaho12 at yahoo.com>; "maxima at math.utexas.edu" <maxima at math.utexas.edu>
>Sent: Saturday, 6 August 2011 7:25 PM
>Subject: Re: [Maxima] Help with very very slow determinant calcuation
>
>
>Is there any reason you're not factorizing the matrix ?
>
>
>2011/8/6 Bernard Hurley <bernard at marcade.biz>
>
>On Wed, 2011-08-03 at 19:26 -0700, Nghia Ho wrote:
>>> Hi all,
>>>
>>>
>>> I'm trying to run the determinant() function a ?10x10 matrix that contains all symbolic values. I've searched through the mailing list to find a solution. I've tried ratmax:true and newdet(), but it is still taking forever. In fact, as of writing now it has been going for over 12 hours and still hasn't finished! Is the determinant doing other stuff besides doing the multiplication and addition? Is it trying to simplify/factorise as it goes along?
>>>
>>> Nghia
>>>
>>> _______________________________________________
>>
>>To evaluate a 10x10 determinant containing independent symbols requires
>>10! = 3628800 multiplications, as well as additions etc. I would expect
>>this to take a very very long time. There are ways of cutting down on
>>this in a numerical matrix or if there are relationships between the
>>symbols.
>>
>>Bernard.
>>
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>>
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