Tutorials: Spreadsheet App

[Tim Wessman]

(09-22-2015 08:10 PM)ndzied1 Wrote:  That was it. Seems silly to me that inside an app you would have to do this but I'm sure there is a reasonable reason for it...

Indeed, there is. At its most basic level, RPN is all about immediate evaluation on entry. Provided you want to SAVE an algebraic expression then, how would you create a formula object in RPN?

The solution they came up with quite a while back (28S/C I think???) is that you have a QUOTE operator that prevents evaluation. To make it simpler, they used ' ' around something to mean quote. Thus in RPN you can do something like 'Y=X+2' and create a formula (algebraic object). It sees the ' and says "Aha. The user wants me to not evaluate the next stuff until I reach a closing ' mark".

When creating the spreadsheet, we wanted you to have the ability to user RPN in there if so desired. Thus any time you are trying to store the FORMULA rather then an immediate evaluation we used the same syntax.

All you are really doing in a spreadsheet with the =A1+B3 or similar is creating a formula you'd like stored in that location. Since RPN already had the syntax for this... we felt we really should use it.