#16237: IncidenceStructureFromMatrix bug
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Reporter: knsam | Owner:
Type: | Status: needs_info
defect | Milestone: sage-6.2
Priority: major | Resolution:
Component: | Merged in:
combinatorics | Reviewers:
Keywords: | Work issues:
Authors: | Commit:
Kannappan Sampath | 44b777a634ee082e1e6f1970d89eac4a2ee67e89
Report Upstream: N/A | Stopgaps:
Branch: |
u/knsam/16237 |
Dependencies: |
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Comment (by knsam):
Replying to [comment:13 ncohen]:
> Hello !
>
> Several remarks:
>
> 1) I do not think you should change the definition of the Paley
matrices... I believe they are well-defined, and if you want a normalized
version of them you should not change their definition but rather
normalize them when you need them. At the very least, you could have an
optional argument "normalize" set to False by default in these functions.
No, I have modified only so much as to remove the edge cases that do not
arise. I am not really changing the definition of Paley matrices. There
are several floating around in the Literature. I have chosen Horadam's
Paley Type I, Type II (I think!). But, this is not standard at all!
>
> 2) You seem to use twice the code to normalize a matrix. I guess the
best would be to write a function that does that, as it can be useful
later, and also useful to the users.
>
Good suggestion, I will implement it!
> 3) There may be a smart way to test if a element of a field is a
quadratic residue, but if you need to enumerate all of them anyway you
could begin by computing the square of all elements of the field, then
decide if each element is a square by testing if it belongs to that list
?...
There are several faster ways to do this! I am planning on implementing
this in a later ticket! But, for now, it shall be a TODO notice!
Kannappan.
--
Ticket URL: <http://trac.sagemath.org/ticket/16237#comment:15>
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