Solver: Changing constraint throws error message, Bug or Misuse?

Hi All,

I am configuring the solver Add-in for a specific problem i would like to run it on.

I am going to try to explain this on a high level, as, as far as I can tell, this seems to be a high-level issue. If digging into the details is required, i will be glad to provide more detail.

Following:

I have a constraint in the solver Add-in, which you can see in following screenshot, marked in yellow ($B$5 >= $B$3 + 1):

Solver1.PNG


I want to change this constraint to

$B$5 >= $B$4 + 1

I try doing this by:

1) Selecting the constraint via mouse-click

2) "Clickling" the "Change"-Button

3) Manually changing the "3" to "4" (see following screenshot)

Solver2.PNG


However, I get following error message:

Solver3.PNG

Not that I think that it should be of any concern to the solver, but both $B$3 and $B$4 are dates, formatted in the exact same way as dates.

Using the unmodified constraint throws no error message from the solver. However changing the constraint from

$B$5 >= $B$3 + 1


to

$B$5 >= $B$4 + 1


throws the error message detailed above in the screenshot.

Have I found some kind of weird bug? Or is there something obvious, that I am missing, in order to get this to work?



THANK YOU!

It seems that certain values in the solver setup can't be "partly" changed. You must change all of i.e delete the "old" value and add the new one.

In my example the range $D$19:$D$26 was defined as integer and trying to change the range to $D$19:$D$24 gives the same warning

a_solv_err.jpg

Could it be that the range is fixed in position (row, column) with the $ when one setup the model?

Alf