[Coin-discuss] Access to dual variable corresponding to a new row

[Matthew Saltzman]

On Wed, 5 Dec 2001, Laszlo Ladanyi wrote:

> Although it is not explicitly stated in the documentation I have always
> assumed so far that new rows are added to the "bottom" of the matrix getting
> the next so many indices and when rows are deleted the rows are reindexed from
> 0 to the new number of rows. Since it's the user who calls the row
> addition/deletion routines she can easily keep track of the constraints.
>
> I admit it's a bit of a burden, but otherwise the row structure must contain
> an index for each row and what would that index be? The index of the row from
> the beginning of times? The user has to keep track of things in that case,
> too, since probably a number of rows would be permanently thrown out, both
> from the solver and from the user's data structures.
>
> All in all I'd vote for keeping things as they are, since it's not clear that
> Osi can take easily over some work from the user.

All the solvers that we have interfaces to now behave the way Laci
describes.

On the other hand, supporting the interface to the solver's MPS name
index is a useful idea.  We're just not there yet.

-- 
		Matthew Saltzman

Clemson University Math Sciences          Editor, INFORMS Online
mjs at clemson.edu                           iol_editor at mail.informs.org
http://www.math.clemson.edu/~mjs          http://www.informs.org