#12220: Updated CBC spkg
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Reporter: ncohen | Owner: ncohen
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.0
Component: linear programming | Keywords: sd35.5, Cernay2012
Work_issues: | Upstream: N/A
Reviewer: | Author: John Perry
Merged: | Dependencies:
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Comment(by ncohen):
Helloooooooooo John ! `:-)`
When I try these patches and the new spkg 2 errors remain in
coin_backend.pyx. The first one is not important (a variable n that
represents a string has been declared as a C integer, it is fixed in a
split second), and the other is in the copy() function. It looks like the
"copied" object is empty (zero constraints, and p.solve() returns 0, ...).
Do you know where this could come from ? `O_o`
Oh, and also : why do you want to cache all the values of the variables in
a dictionnary attached to the CoinBackend object ? To me it is doing too
much work, as the user does not always want to read ALL the variables
(some are just there to define constraints) and sometimes none at all
(just interested in the optimal value of the LP, or in its feasibility).
The other point is that storing values in Python lists is *MUCH* more
expensive than storing them in C arrays. Because a dictionnary is
expensive, and because it does not store C floats but pointers to Object
representings floats.... `:-P`
It would be nice to see this patch merged in Sage 5.0. Anyway thanks for
all the work you did on this ticket `:-)`
Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12220#comment:68>
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