Referring to unset custom number field

[AXG]

I have to track a ratio of financial benefits in all projects. I am using a
series enterprise task custom number fields with 'sum' roll up for the
benefits and an enterprise project custom number field for the ratio and an
enterprise custom text field (with value list) to indicate which two fields
of the series are to be used for the ratio

It is allowable to have a zero value for these special financial benefits

The ratio formula uses the switch function with a initial expression that
sets the ratio to 1 if the sum of possible denominators is zero. But until I
set a non-zero denominator the ratio field always is #ERROR

I have tried using the IsNull function with ANDs but get the same #ERROR.

Any ideas anyone?

 

[JackD]

You get the #error because you are dividing by zero.
Maybe you can work with the inverse of the ratio until you have proven that
the value is defined (ie: your denominator is not 0.

If you want a better question to this answer then it would be a good idea to
post the formula you are using.