Making sure variable is an integer?

**Mooshey** · 02-03-2008, 02:42 PM

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** · 02-03-2008, 02:50 PM

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

Can you post a workbook?

**shg** · 02-03-2008, 03:07 PM

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

       --A--- -B-- -C-- -D-- ---E--- -F- -------------G-------------- --H-- ----I-----
  13   Profit wood prod time Fitting box           Formula            Value Constraint
  14   tables 215   70   20    72     1              =20*x + 12.5 * y  6000 <= 6000   
  15   chairs 136   30  12.5   18     1                        =x + y   351 <= 400    
  16          > 0  > 0                               =72 * x + 18 * y 17928 <= 18000  
  17                                     =SUMPRODUCT(B14:B15,D14:D15)  6000 maximize

**Mooshey** · 02-03-2008, 04:39 PM

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

**Mooshey** · 02-03-2008, 04:43 PM

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

**shg** · 02-03-2008, 05:23 PM

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.

Making sure variable is an integer?

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