#17663: Clean up sparse matrices
-------------------------+-------------------------------------------------
Reporter: | Owner:
vdelecroix | Status: positive_review
Type: | Milestone: sage-6.5
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers: Martin von Gagern
linear algebra | Work issues:
Keywords: | Commit:
Authors: | d292e6ff17ea1815e5b24267a6d0140ea5598add
Vincent Delecroix | Stopgaps:
Report Upstream: N/A |
Branch: |
public/17663 |
Dependencies: |
#17658 |
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Changes (by vdelecroix):
* status: needs_review => positive_review
Comment:
Replying to [comment:31 gagern]:
> Replying to [comment:19 vdelecroix]:
> > It depends on the school! "my_var is None" is a simple address lookup
while "not my_var" implies a function call. So "my_var is None" is very
fast compared to "not my_var".
>
> Valid point, so I won't object to leave the code as it is. Might even
adapt that style.
;-)
> > > * `_cmp_backward` might use `if i != j: return i - j` in the first
case as well. Not sure whether that makes much of a difference.
> >
> > Actually this is what I tried. But if you do that, you end up with
some warning claiming that the comparison routine returns something
different from 0,1,-1!
>
> Can't reproduce such a warning. Who is complaining when? Why no warning
for the other pair component? I wonder whether one would want to put some
bigger numbers in the test case, in order to make sure that steps with
absolute value more than one are always involved in some comparison. But
even then I don't see this warning you mention.
At some point, I had trouble with this but I do not remember exactly. I
just learn a funny way to do it returning 1,0 or -1 fast:
{{{
return (i > j) - (i < j)
}}}
> My question about the `The input must be scalar or a dictionary`
exception being dead code (from comment:23) still stands. I just pushed a
commit for that. If you have no objections to it, feel free to mark this
as positive review, since I'm happy with your changes.
Thanks for that!
Vincent
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Ticket URL: <http://trac.sagemath.org/ticket/17663#comment:32>
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