Enabling Iterative Calculation – How to use

[sdruley]

I have a very complex workbook that, out of necessity, has some circular references. As a result I have “Enabled Iterative Calculation” and it appears to be doing fine except as more data enters the program the calculations are beginning to slow down and the final output of the program, which is a single number, seems to jump around a bit as the calculation burden increases.
Whilst the true, expected number is 368.50 I am getting a spread of numbers as follows
352, -432, -121, -169, 71.50, -474, 368.50.

To correct this inconsistency how do I adjust the maximum iterations and maximum change to minimize the spread. My current setting is 500 iterations and .0001 Maximum Change.