A Note on In-Cell Iteration

Suppose that in a spreadsheet the following formula is entered into cell Bl  

Since cell reference Bl is in the formula of the same cell, this is called a circular reference. Normally, Excel will complain about this. However, if the Enable Iterative Calculations (see File/Options/Formulas) box is checked. Excel will immediately do the following  

It will automatically use an initial guess of zero (there is no control over this). 

It will iterate up to 100 times or until successive values are within 0.001 (these values can be changed). 

In-cell iteration is not to be encouraged when robustness is a goal. It often fails to find a solution. 

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