Hypatia Open Source RPN Calculator for Windows


Hypatia is a powerful programmable text based RPN (Reverse Polish Notation) calculator for Windows.

Despite its many advanced features, Hypatia is easy to use for simple calculations. Everything you do not need, you can just ignore.

Hypatia has a very small footprint, consists of only one small executable file, is fast, does not touch the registry, does not phone home, and does not read or write any files except in its own program folder.

Hypatia is free and open source (see “License” below). Hypatia is written in Phix, phix.x10.mx

The name Hypatia is a tribute to the mathematician, astronomer and philosopher Hypatia of Alexandria.

For other tools, see here.


User Manual (PDF file, also included in the download zip file)

Download Hypatia for Windows (zip file, 0.6 MB, includes user manual)

Version 2.6, September 7, 2023

The zip file includes the executable hy.exe, the file readme.txt, the user manual hypatia-doc.pdf, and the source files, which you can ignore unless you want to study them or modify the program.

Version 2.6 adds a new feature that lets you address individual values in data read from files.

Version 2.5 contained important bug fixes, please update if you have an older version!

Expect a new version in early January 2024. I’m always open to suggestions (also regarding the documentation) — and, of course, tell me if you find a bug, or some unexplained behavior. If you want to be informed when a new update is available, send me a message (see below).

Hypatia’s Linux version is still experimental, and unless someone is interested to help with it, will probably remain so.


- Create an empty folder, and unpack the zip file into it. You can delete the \source folder and the file readme.txt after you’ve read it. Keep the zip file, just in case.

- Create a link to hy.exe on your desktop: right-click hy.exe, go to “Send to”, click “Desktop (create shortcut)”, and then rename the icon “Hypatia”. (Yes, I know, the icon isn’t pretty, maybe I can come up with a nicer one some day.) You can edit the icon properties to customize Hypatia’s console window.

- To use Hypatia from the command line: add the folder with hy.exe in it to the system path. (If you are familiar with the Windows console or the PowerShell, you probably know how to do this. If not, you don’t need to.)

For more information, see readme.txt and the chapter “Installation” in hypatia-doc.pdf (page 6).


Hypatia uses its own enhanced version of RPN (Reverse Polish Notation).

Apart from the usual functions of a scientific pocket calculator and a number of built-in unit conversion functions, Hypatia knows named variables, lets you define your own constants, lets you define your own functions and write your own scripts, knows hexadecimal and binary numbers, lets you read data from files, has count and condition controlled loops, If/Then/Else clauses, can do iterative calculations, knows three kinds of random numbers, lets you perform Monte Carlo experiments, lets you calculate generalized Fibonacci sequences, lets you export sequences of results, etc., etc.

The strictly text-based approach may come with a steeper learning curve for non-trivial tasks, but brings a number of significant advantages — for instance, you can scroll through past inputs, edit and re-use them, log and export them, and your own functions and scripts use exactly the same syntax as your calculations and seamlessly integrate with them.

Hypatia can be run from the desktop or from the Windows command line. You can even perform calculations directly from the Windows prompt without opening Hypatia.

The main limitations are: While Hypatia can calculate standard deviations, medians and three types of means, it is not a tool for statistical analysis. Hypatia does not know matrixes, vectors or arrays, nor does it know imaginary or complex numbers. Internal accuracy is 14–15 decimal digits, of which 12 digits are shown.

Why use Hypatia?

I can think of three reasons:

- You like RPN, or want to get acquainted with it.

- You like small, fast, puristic and powerful text-based tools, particularly when they are open source.

- You’re not a fan of either, but you’re willing to compromise because among Hypatia’s many features there are some that you find useful and haven’t found somewhere else.

Anyway, you only need a few minutes to download Hypatia and take a look. It doesn’t interfere with your computer, doesn’t read or write anything outside of its own program folder, and leaves no traces when you remove it — so, just give it a try!

By the way, Softpedia has given Hypatia quite a favorable review:



No legalese, just very simple rules.

You may do with the executable file, the documentation, and the source code whatever you want, under three conditions:

- that you credit the original author,

- that you document the changes you have made, at least in general terms, and that

- you are under no circumstances allowed to modify this program in a way that could be potentially harmful to the user, or to distribute it in a potentially harmful way.

The executable, the source code and the documentation are offered “as is.” No warranty of any kind is provided or implied. All support is given voluntarily.


Feedback is essential. Please tell me if you've found or suspect a bug, if you found an error in the documentation, or if you find parts of the documentation to be unclear, incomplete, or difficult to understand. If you have questions, just ask me.

I’d also like to hear if you find the program useful, if you’re happy with it, or if you have any suggestions or complaints.

Robert Schaechter, Vienna/Austria, e-mail: robert@drs.at

Please put “Hypatia” in the subject line of your message.

What’s New:

September 7, 2023: Version 2.6 — LIST command renamed to FILES, new ABORT command, and one major new feature, the ITEM operator.

March 28, 2023: Version 2.51 — basic information displayed on first program start.

March 20, 2023: Version 2.5 — fixed two bugs (one old, one new), and added n-argument delimiter.

March 19, 2023: Version 2.4 — Hypatia now displays numbers with up to 12 (previously 10) digits.

March 9, 2023: Version 2.3 — new commands SKIP, = and ==, new pseudo constant ISLOOP, some minor additions and a bug fix.

March 2, 2023: Version 2.2 — new PROMPT command, “run files” are now called scripts.

February 22, 2023: Version 2.1 — a number of minor additions and improvements.

February 2, 2023: Version 2.0 — new loop command, new If/Then/Else features, plus a number of minor additions and improvements.

January 14, 2023: Version 1.2 — adding new features, particularly in the context of loops.

December 14, 2022: Version 1.0 — finally, after 15 years! There is, of course, some arbitrariness in naming a version 1.0, but all the features are there now, and, hopefully, most of the bugs removed. Keep checking for updates, though.

November 2, 2022: This website is online, with version 0.99 — getting close to 1.0.

Apart from this …

If you are interested in literature and e-books, please visit my free Dunyazad Digital Library e-book website:


There you can also find some command line tools, which I plan to move them here in the future: