Excel Solver ignoring sum constraint

[cmeiss16]

I created a solver in which F8 is maximized with the only constraint being E12 (the sum of bets) <= total bankroll (in this case I just set it to $100). This constraint is being completely ignored and I get error messages because the system tries to take the log of a negative number, something that wouldn't happen if the constraint was followed. Why is the constraint ignored? Any way to fix it?

[Pepe Le Mokko]

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Thanks

[MrShorty]

I did not replicate your problem. When I opened your file and ran Solver, it had not trouble solving the problem. My older version of Excel does not have all of the same Solver engines available, so my first guess is that something in the chosen Solver engine does not like the exact problem you gave it.

A few things to look at:

1) Solver engine -- My older version uses a Newton-like algorithm (as I understand it -- should be similar to the GRG-nonlinear option in newer versions). Perhaps try a different Solver algorithm.
2) Choose better initial values. I notice that your default initial guesses seem to be $0 for each. You might try entering some different values for these initial guesses. Some problems require more care in choosing initial guesses than other problems.

I cannot replicate the problem here -- probably something related to the available solver engines in my older version, so I cannot give any better suggestions.

[cmeiss16]

I started messing around with starting variables to try and create some methodology to pinning the answer down. It's not an exact science and I doubt I'll achieve fully optimal solutions for data with heavy favorites, but it's a step in the right direction.

Thank you for your help!