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 still 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 a text-based 64-bit Windows console program. There is no graphic interface, you need to use the keyboard instead of the mouse.

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.

Download Hypatia 4.0

Download Hypatia for Windows (zip file, 0.93 MB, includes user manual)

Version 4.0, April 2, 2024

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

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

Please get the latest version of Hypatia if you are using an older one!

From version 4.0 on, Hypatia requires a 64-bit Windows system. I had originally planned to keep offering 32-bit versions, but maintaining two parallel versions of Hypatia turned out to be too much effort, sorry.

I’m always open to suggestions — and, please tell me if you find a bug, or some unexpected or 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 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 7).



Simply replace hy.exe and the PDF documentation files with the new versions.


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 and save results to 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.

Integers can have up to 18 digits. Internal accuracy for floating point numbers is 18 digits, of which up to 15 digits are shown.

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.

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 or vectors, has only a limited understanding of one-dimensional arrays, and does not know imaginary or complex numbers.

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 anywhere 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.

Please also tell me 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:

April 2, 2024: Version 4.0 — a major overhaul, a few new operators and commands, and a move to 64 bits, which allows for 18-digit integers and 15 significant floating point digits.

February 12, 2024: Version 3.4 — lakh, million and crore can be used for large numbers, new loop timer, some minor improvements. PRIME operator renamed ISPRIME.

January 24, 2024: Version 3.3 — new BUFFER SAVE command.

January 20, 2024: Version 3.2 — new compare operators, and the ITEM operator now accepts negative index arguments.

January 4, 2024: Version 3.0 — new “user defined elements,” new “buffer mode,” INIT command renamed RESET, a number of smaller additions and improvements, documentation partly revised, and a new quick reference guide.

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

A complete “Release Notes” list can be found at the end of the user manual.

Apart from this …

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