It would be very useful to be able to create a calculated field on a report
For example we have a module that has a selling price and a cost price
It would be useful when reporting to work out the margin and margin %
good idea !
You could easily create Logic Hook (for example before_save) that does it for you.
You could also do it with a scheduler to do it (in this case the value would not be updated until the scheduler has run)
In fact my suggested solution may be easy to implement to calculate the value and save it into a field which, in turn could be inserted into a report.
At present I do create a field and populate it
But sometimes when writing a report you want todo a calculation that you hadnt thought of when creating the module
I then have to add a new field
It would be much easier to have a calculated field you create when creating the report
I understand. Unfortunately the way you would like to achieve it does not seem to be feasible currently.
Yup I know you can’t do it at the moment
Thats why its a suggestion for the future 