but there are some problems that can't be solved without a circular reference.
Can you provide an example? I'd tend to think that in all cases a little algebra could be used to move all the cell's terms to be alone on the left of the "="
Actually, I can't provide it. It's highly proprietary pertaining to very complex chemical reactions, but there are practical reasons why I also can't set up Numbers in the ways that have been suggested. The main one is the sheer magnitude of trying to do it. Another one is I'm not really qualified to do it. Here's an example of what I deal with routinely:
First, in one example, I have a formula that involves one circular reference and reference to nine other cells many of which refer further to other cells. That single formula involves 5 multiplications, two additions, two subtractions, and one division.
Second, Excel usually goes through several hundred or sometimes several thousand iterations before finding the "answer." In Excel 2008/Mac, you go to "Preferences: Calculation" and set the "maximum iterations". I use 10,000. I also set "Maximum change" to 0.001 (meaning that, if the iteration change gets smaller than that, the calculation stops. To me, that should be labeled "minimum allowable change." Then select "Calculate Sheets: Automatically" and Excel goes to work. The labeling in this calculation function doesn't distinguish between circular references and unknown values where circular references are not involved. It handles them all.
Unless Numbers is expanded to possess the functionality and capacity of Excel, I'm afraid I'm stuck with Excel. Before I started this thread, I had spent quite a bit of time snooping around Numbers and its User Guide, but I couldn't find anything on the kind of calculations mentioned here, so I thought I'd better call in the heavy artillery in this forum just in case I'd missed something. From this discussion, it appears that Numbers doesn't yet have all of Excel's calculation features. Since I don't consider myself qualified to produce a do it yourself solution, it seems my only real option is to stick with Excel. I appreciate the suggestions very much, but I think I need to stay where I am until Numbers is brought up to Excel's capacity. BTW, I really enjoy this forum. You folks are smart, knowledgable, and very experienced. Thanks for the input.
