Thank you for the feedback thus far. My issue is that I can use Solver to find an optimal solution if I don't use my user defined function (UDF). Instead of using the UDF I have defined the model in a worksheet (it is exactly the same as the UDF but stores the intermediate calculations). When...
As you requested, I have saved the excel file in the older version, and attached it.
As for the threads that I was referring to (I am not sure if there is a better way to give you this information). The threads I was referring to were:
http://www.eng-tips.com/viewthread.cfm?qid=220835&page=1...
I have encountered a problem with using Solver to optimize some of the inputs of a user defined function. I would like to use Excel's Solver to minimize the sum of the square errors between observed data and a model.
I read some other posts or threads that dealt with the same issue. I believe...