Re: Slow performance on "Select minimum" task
Jan van Rijn <[email protected]>
| Newsgroups | gmane.comp.gnu.glpk |
|---|---|
| Message-ID | <CAJ=jOAx0LkAABd7C=TGr=9hdp6o_nR59AJKKerbK0R_iapq7qw@mail.gmail.com> |
I'm not sure if that is entirely the case. The way I interpreted your solution was that 'at least one y-value per column will be >= 1'. I don't see exactly which constraint makes sure that there will be exactly one y-value per column 1 (which, again, we don't need if all values in M are >= 0). If M contains negative values, it could be that: * an ideal solution would have multiple y-values per column bigger than zero, and * These values will not necessarily be one, but can take even higher values (due to this GLPK gave an error message, and this is how I found out) Sorry if I am missing something obvious. The current solution seems to work like a charm so thanks again :) Best, Jan 2018-06-06 10:06 GMT-04:00 Michael Hennebry <[email protected]> : > On Tue, 5 Jun 2018, Jan van Rijn wrote: > > 2018-06-05 23:39 GMT-04:00 Michael Hennebry <[email protected] >> u> >> : >> >> On Tue, 5 Jun 2018, Jan van Rijn wrote: >>> >> > - M[r,c] should contain positive values (which guarantees that y[r,c] == 1 >>> >>>> iff x[r] - SUM x[s] == 1) >>>> >>>> >>> I'm pretty sure that is not necessary. >>> the y's depend only on the x's and the order of the M values. >>> In any case, I think the zeros in your original problem >>> will not be much of an issue. >>> >>> >> >> I should rephrase: The array should contain values >= zero. >> (negative values are an issue, but these can be scaled away easily. ) >> > > I'm not sure where that is coming from. > The y's are determined by the x's and by sets > of rows determined by the order of the M values, not their signs. > Only one y value in a column can be one. > > > -- > Michael [email protected] > "Sorry but your password must contain an uppercase letter, a number, > a haiku, a gang sign, a heiroglyph, and the blood of a virgin." > -- > someeecards > _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk