When I was working as an engineer, I fell in love with the RPN calculators produced by HP. Once one gets used to the concept, RPN is a fast and elegant way of entering complex calculations while displaying intermediate results on the fly. However, as much as I love RPN, it doesn't make it easy to verify that you entered the whole calculation correctly, which is something that today's textbook format calculators do very well.
So, the thought occurred to me, why can't a calculator do both? Why not enter calculations using RPN just like the old HP calculators, but then display the calculation in textbook format on the stack along with the answer? Then on top of that, make it possible to go back and change the calculation numbers, or undo the calculation entirely and move the parts around the stack and redo it again? That's what I created Visual RPN Calculator to do - combine the fast and elegant input method of an RPN calculator with the ability to verify and edit your calculations like an algebraic calculator.
I chose to implement my idea on Windows 10 using C# and Visual Studio because Microsoft has a reputation for making a good tools which I wanted to learn. Once I chose Universal Windows Platform (UWP) as my target, I wanted to make the calculator interface fit the platform, not be an emulation of an HP calculator on windows.
My first windows store submission back in July 2016 was pretty basic, but over time I've added more features on a regular basis - sometimes in response to requests from users (if you want something, click on the feedback button on the calculator under the hamburger menu or email me at email@example.com).
Over time Visual RPN Calculator's feature set has been slowly building up to approach the calculators which cost lots of money at the store:
The biggest change I'm working on right now is making Visual RPN Calculator truly programmable, with an RPN based programming language that includes conditionals, looping and all the others features one expects in a full featured (if slightly basic) programming language. Of course creating a language is only part of the battle. The larger part of the effort will be making the calculator a programmer friendly environment with program entry, debugging etc. - which honestly may take a few iterations to get perfect.
There are also a few other items I want in the calculator that I'll be getting to as time permits:
Visual RPN Calculator has an option to store and load calculator state to a file and folder of the users choice. Also, the app has access to the internet so it can send formulas to the Wolfram Alpha website and so it can access this webpage, though it also works fine without internet. Other than that, the application doesn't mess with any of your files, and no other data from your computer is ever accessed by this application or shared over the internet.