Danie van der Merwe

“I’m Not Dead Yet!” Reverse Polish Notation Calculators You Can Still Buy

2026-09-02 14:42:22

gadgeteer@hub.netzgemeinde.eu

“I’m Not Dead Yet!” Reverse Polish Notation Calculators You Can Still Buy

“RPN isn’t exactly the way people calculate with pencil and paper, and it certainly wasn’t derived from the slide rule, but there is a similarity in the way you work. With a slide rule, you generally establish some value, operate on it, and continue from the result. When doing a long-hand calculation, you often calculate a subexpression, write down the answer, and use that answer in the next step. You will probably start with the inner parenthesis and work outward, just like someone with an RPN calculator does. RPN formalises that process with a stack.”

I still have my HP41CV, and it still works well 40 years on. RPN is actually a highly effective way of doing complex calculations. Once it is understood, it is quite intuitive. My HP41CV was RPN-only, so I got very used to using it.

It is good to see there are still options available to buy, and I did not know about the Linux AppImage for HP Prime Virtual Calculator. Neither had I seen the CalcTastic Android app — must say it works very nicely, and I do love the many theme options.

See “I’m Not Dead Yet!” Reverse Polish Notation Calculators You Can Still Buy

If you used a scientific calculator in the 1970s or 1980s, there was a fair chance that it worked differently from almost every calculator you see today. Instead of typing: 2 + 3 = you entered: 2 E…

#technology #RPN #calculators

technology RPN calculators

In praise of Reverse Polish Notation (RPN) with Python or C

2023-06-21 14:39:44

Danie van der Merwe

gadgeteer@hub.netzgemeinde.eu

For whatever reason, RPN didn’t really succeed in the general marketplace, and you might wonder why it was ever a thing. The biggest reason is that RPN is very easy to implement compared to working through proper algebraic, or infix, notation. In addition, in the early years of computers and calculators, you didn’t have much to work with, and people were used to using slide rules, so having something that didn’t take a lot of code that matched how users worked anyway was a win-win.

With RPN, there is no ambiguity depending on secret rules or parentheses, nor is there any reason to remember things unnecessarily. Processing RPN, on the other hand, is easy. If you see a number, push it on the value stack. If you see an operator, pop off enough stuff from the stack, do the operation, and put the result back on the stack.

See In Praise Of RPN (with Python Or C)

#technology #Python #math #RPN

HP calculators, slide rules, and Forth all have something in common: reverse polish notation or RPN. Admittedly, slide rules don’t really have RPN, but you work problems on them the same way …

technology math Python RPN

2023-06-21 14:49:44

Uncle Mikey

belmikey@mstdn.social

@gadgeteer Honestly, I always felt this was just a matter of how we're taught. We're not taught RPN young; we're taught a simplified algebraic notation and then it gets progressively more complex until we're full-blown algebraic. Unless we start learning computer programming or get into a class that uses fancy HP calculators, people can go their whole lives never encountering RPN, which makes it basically a second language at best for most people.