I think you are going to have to be more specific in what it is you want to do. I for one do not know what "SFN" is nor "Net Present Value." You may get lucky and someone will know what those terms are, and maybe even the correct context you are referring to, but I doubt anyone is going to spend time looking it up and then write a script for it.
I think "SFN" is 'Simplified Field Notation". And the 'Simplified Field Notation' option of the calculation tab does not support any function.
There is no Net Present Value function defined within Acrobat or JavaScript. But you can perform addition (+), division (/) and exponentiation (Math.pow(10,n) ) with JavaScript, so you can write your own custom calculation script to perform the computation. I would suggest that you write it as a function with passed parameters.
I think you are going to have to be more specific in what it is you want to do. I for one do not know what "SFN" is nor "Net Present Value." You may get lucky and someone will know what those terms are, and maybe even the correct context you are referring to, but I doubt anyone is going to spend time looking it up and then write a script for it.
Dimitri
WindJack Solutions
www.pdfscripting.com
www.windjack.com
Dimitri Munkirs
WindJack Solutions
pdfscripting.com