Circular references within a model are supported as long as Iteration is selected on the Tools, then Options, then Calculation tab in Microsoft Excel.
(In Microsoft Excel 2007 or later, click the Office button and select Microsoft Excel Options, then Formulas, and then select Enable Iterative Calculation in the Calculation Options group.)
If Crystal Ball detects a circular reference and Iteration is not selected, this error is displayed:
Example message: "Circular reference detected at cell [Book1.xls]Sheet1!A1. (Code #5523)"
Workaround: Stop the simulation and select Iteration on the Tools, then Options, then Calculation tab.
In Extreme speed, circular references with short Iteration setting may not match Microsoft Excel’s values because of differences in calculation algorithms. For most consistent results, set Iteration to at least 1,000.
However, if a circular reference is non-converging, its results can differ greatly when run at both Extreme and Normal speed, regardless of the Iteration setting. If a circular reference is non-converging, this error message is displayed:
Example message: "Unable to run in Extreme speed for the following reason: Circular references do not converge, results cannot be guaranteed to match Normal speed. To bypass this message, turn off "Stop on calculation errors" in the Run Preferences dialog. (Code #5545)"
Workaround: There is no workaround. Review the formulas in the workbook that have created this circular reference and look for a problem that keeps this circular reference from converging to a single value.
Simulations with circular references run in non-vectorized mode. For this reason, they will probably run more slowly than simulations without circular references.