Excel Solver Ignoring Constraint in VBA

Question

I am trying to find a maximum return for a simple portfolio using Solver. Using Solver in the worksheet directly works sensibly, however it does not when the commands are set in

Answer 1

I think there is a bug here whenever the value is exactly 1. Other postings state that the above solution (putting the value into a cell) is unreliable. I have found it does not work a my code always refers to a cell which holds the constraint limit. My (crude) solution is to shift the limit value by 1 part in 10^12 or lower in the appropriate direction which sort of makes the constraint into a < or > rather than a <= or >=. So rather than:

SolverAdd CellRef:=Range("SolverParam").Address, Relation:=3, _ FormulaText:=Range("SolverConstraint").value

Use:

SolverAdd CellRef:=Range("SolverParam").Address, Relation:=3, _ FormulaText:=Range("SolverConstraint").value + Abs(Range("SolverConstraint").value) * 1e-12

And use the opposite sign for Relation:=1

In this trivial example SolverParam is a single cell parameter to be adjusted and SolverConstraint is a single cell lower bound.

This is the only consistent approach I can foresee to have a uniform handling of all values

On further looking I found another solution from the web

FormulaText:="=" & Range("SolverConstraint").value

Seems to work reliably

Answer 2

I had the exact same issue. I solved it in the following way: Just type FormulaText:=1 without the quotes for 1.

Answer 3

Found a work around for the bug. For the flag "FormulaText:=1". instead of using 1, use a reference to any cell with the value 1 instead.

I.e., Change "FormulaText:=1" to "FormulaText:=$H$5" where $H$5's value is 1