Making sure variable is an integer?

[Mooshey]

Hi,

I am doing some linear programming, and I want to indicate to Excel that the X and Y variables are number of tables and number of chairs. Therefore cannot be negative and must be integer values.

I wrote the following example and the x is B14 and y is B15 cells. How do I indicate that B14 and B15 cells are integers?

Profit wood prod time Fitting box
TABLES tables x 70 20 72 1
CHAIRS chairs y 30 12.5 18 1


Restrictions Limit
20x + 12.5y <= 6000
x + y <= 400
72x + 18y <= 18000
X>0 Y>0

Objective
=sumproduct(B14:B15,D14:D15)

[shg]

Are you using Solver? There is an integer constraint for cells.

Can you post a workbook?

[shg]

If I did it right, I get 215 tables and 136 chairs:

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[Mooshey]

I got 216 and 133.
It doesn't let me upload the xls file..

[Mooshey]

You mentioned that there is an integer constraint for cells. Where is it in Solver?

[shg]

I got 216 and 133.

That results in 5982.5 for SUMPRODUCT(B14:B15, D14:D15); 215 and 136 returns 6000.

You mentioned that there is an integer constraint for cells. Where is it in Solver?

It's one of the selections in the operator dropdown in the Add Constraint dialog.

[Mooshey]

Hi,

I found how to add integer constraints.
For some reason I get 217 and 132....

I appreciate your help,
Tlalit

[shg]

See attached. Set x and y initially to 1.

[Mooshey]

Thank you.
I have added the ing constraint to Solver.
Is there a way to make sure that solver rounds the variables down?
I am thinking that if we are talking about a factory that makes tables for example, the rounding should always be round-down type, because rounding up might mean that we are using materials or time that the factory doesn't have.
Does it make sence?

[shg]

Does it make sence?

Not to me, no.

Solver operates according to its specified constraints, which include the time, materials, and any other resources within which the solution must fit, and constraints on the solution (integer values in this case). It optimizes the evaluation function subject to those constraints.