#16504: Fix the confusion in MILP.new_variable()
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Reporter: jdemeyer | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.3
Component: linear programming | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by ncohen):
Yes, it would be easy. The main problem is that if you want to change the
current behaviour of the function (i.e. if you want nonnegative=False to
be the default) then you will have to "make nonnegative mandatory" for a
while and raise a warning when it is not set. Otherwise when you will
change it, guys who currently use "integer=True" to mean "nonnegative
integer" will find themselves with LP returning weird answers.
That was the point of #15521.
Also, it may seem weird to see all these variables be nonnegative by
default but that's really the standard for LP solvers. The LP backends
really assume non negativity unless asked otherwise, and changing the
standard in Sage is really something that we do "for the general
mathematicians knowing that it could surprise guys used to LP".
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/16504#comment:2>
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