#12103: Use MeatAxe as an optional back end for dense matrices over `GF(p^n)`, p
odd, n>1, `p^n<255`
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Reporter: SimonKing | Owner: jason, was
Type: defect | Status: needs_work
Priority: major | Milestone: sage-6.4
Component: packages: | Resolution:
experimental | Merged in:
Keywords: linear algebra, | Reviewers:
MeatAxe | Work issues:
Authors: Simon King | Commit:
Report Upstream: None of the above | 106aeef1f449f7db3a617e986d2e697865ee34ac
- read trac for reasoning. | Stopgaps:
Branch: |
u/SimonKing/meataxe |
Dependencies: |
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Comment (by SimonKing):
Replying to [comment:89 SimonKing]:
> Meanwhile I know that the wrong results of Strassen multiplication in
field order 2 come from the function `FfAddMapRowWindow`, which in fact
has a special case for the field of order 2. This function is a
modification of the !MeatAxe function `FfMapRow`.
Got it! There is a pointer that is moved through the matrix by which we
are multiplying. In case of order two, if an addition of a row happens
then the pointer is moved to the next item after the current row of the
matrix.
In `FfMapRow`, this position automatically is the first item of the next
row of the matrix. In `FfAddMapRowWindow`, the matrix is in fact just a
window of a larger matrix, and this position generally is outside of the
window. Hence, I have to manually move the pointer to the first position
of the next line of the window.
--
Ticket URL: <http://trac.sagemath.org/ticket/12103#comment:93>
Sage <http://www.sagemath.org>
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