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Re: [apple scitech] Re: Accelerate Framework: Calculate Determinant

Hi James,

Yes, this is what I have just found too.

Using the apple blas library improves speed my about 5%-10%, compared with hand coding the determinant.

Any ideas on how to get it faster?

Dan.

On 1 Nov 2007, at 17:04, James Meiss wrote:


On Nov 1, 2007, at 10:36 AM, Daniel J Farrell wrote:

Hello,

Yes it will always be a 4x4. I have written a 'long hand' function in which I have written out the the determinant as its sequence of multiplications and additions.

How can I vectorise this? It has about 90+ terms?

In your experience would it we worth 90+ calls to vDSP_mul?


Gaussian elimination requires (n^3-n)/3 multiplications to get the matrix into upper triangular form (albeit with a some pivots, etc). Even for n=4 (where the number is 20), this should be much more efficient than the explicit formula.


--
Jim Meiss
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 >[apple scitech] Re: Accelerate Framework: Calculate Determinant (From: Daniel J Farrell <email@hidden>)
 >Re: [apple scitech] Re: Accelerate Framework: Calculate Determinant (From: James Meiss <email@hidden>)



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