|Re: [eigen] FLENS C++ expression template Library has excellent documentation|
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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] FLENS C++ expression template Library has excellent documentation
- From: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>
- Date: Sat, 18 Apr 2009 23:11:29 +0200
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On Sat, Apr 18, 2009 at 10:33 PM, Ilya Baran <baran37@xxxxxxxxx> wrote:
>> On Sat, Apr 18, 2009 at 6:06 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
>>> I really mean to implement Block LLt or partial LU soon, it can be
>>> written cleanly with Eigen blocks.
>> Actually, I've already tried a block LLt implementation (so using BLAS
>> 3 routines) and it was slower than our current level 2 based
>> implementation. so... I wish you good luck as it seems not to be so
>> trivial to get higher performance !
> All three variants from FLAME use syrk (A^T * A) which is currently
> half as fast in Eigen as it could be. Could that explain the
> performance penalty or did you use another blocked method?
I think you get a good point. I lost the code, but I remember the
bottleneck was the matrix-matrix product (even when using MKL for this
step). So first step implement a fast syrk....