Applies to:
Evolver 4.x and Up
RISKOptimizer in @RISK 5.x–7.x Industrial Edition
Evolver Developer Kit 4.1
RISKOptimizer Developer Kit 4.1

Unique Integer Adjustable Cells (No Duplicates) in Evolver or RISKOptimizer

 

If you have a set of adjustable cells that must contain integer values and must also be unique in every trial (no duplicates), you can enforce this with a helper-cell constraint.

Tip (simplest case)
If the number of adjustable cells equals the number of possible values (so each trial must use all values exactly once), simply use the Order method. No constraints are needed.

 

General method (works for all cases)

Step 1. Create helper cells to count duplicates

Assume your adjustable cells are in A14:A28.

In B14, enter:

=COUNTIF($A$14:$A$28, A14) - 1

• $A$14:$A$28 is an absolute reference to the full adjustable range

• A14 is a relative reference to the current cell’s value

• Subtract 1 because COUNTIF includes the cell itself; we want only duplicates

Copy this formula down from B14 to B28.
Each helper cell now counts how many times the value in column A is duplicated elsewhere.

Step 2. Sum the duplicates

In a separate cell (for example B31), enter:

=SUM(B14:B28)

This cell shows the total number of duplicates in the adjustable range.

Step 3. Add a constraint

In Evolver or RISKOptimizer settings:

• Define A14:A28 as adjustable cells (integer range as needed)

• Add a hard constraint:

  B31 = 0
  

This forces every trial to have no duplicate values.
You do not need individual constraints on B14:B28.

Step 4. Start optimization

Begin the optimization. Any trial containing duplicates will be rejected automatically.
For best performance on large models, turn off Update Display.

Best practice: start with a feasible solution (no duplicates) before running optimization.

 

 

Attachments:
KB257_NoDupes.xlsx