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Old 2020-10-04, 17:33   #1
Sep 2011

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Default trying to implement block lanczos on GF2...

Hi, I'm currently trying to implement Block Lanczos, but I'm having some trouble understanding the notation on calculating Si and Winv. I'm reading Montgomery's paper and Yang et. al.'s pseudocode (attached).

On line 13 of the attached file, the algorithm seems to create a set S of row & col where a 1 is found. Eventually I need to compute Si*SiT based on S. I think to form Si*SiT I just need to set M[x,x] = 1 for each x ∈ S. M is a square matrix with side size of machine word (as defined by the paper) rows and cols. Is this correct?

Also, Si-1 is an input to this function, but I don't see it was used there. What am I missing?
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Last fiddled with by paul0 on 2020-10-04 at 17:56
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