Choice of data entry among interrelated fields

['makerphile]

Suppose I have have two fields: "double" and "half". For a given record, the value of double will be twice that of half (e.g. double = 4, half = 2). Sometimes it will be convenient to enter data for half (e.g. 2), in which case one wants data to be calculated and entered automatically for double (e.g. 4). At other times, entering data into double will be more convenient, in which case one wants half to be calculated automatically. What are some approaches to providing flexibility like this in choosing among fields for data entry?

[comment]

Set the Double field to auto-enter a calculated result (replacing existing value) =

Case ( Get ( ActiveFieldName ) = "Half" ; 2 * Half ; Double )

and a similar thing for the other field. Note that it will break if you rename the fields (this was solved in version 10).

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BTW: semantically, if half = 2 then double = 8.

['makerphile]

Sorry it took so long to thank you. That worked.