EC, a terminal-based RPN calculator

EC (binary: ec) is a terminal-based RPN calculator inspired by Hewlett-Packard’s venerable HP 48 line. It aims to be the calculator of choice for the discriminating computer scientist.

EC is ready for everyday use. It supports the four basic functions, powers and roots (with sq/sqrt and pow/xroot), logarithms (ln/exp for base e, log/alog for base 10), and trigonometry (sin/cos/tan/asin/acos/atan). It is accessible via a batch mode (try echo 2 2 + | ec), and if invoked interactively, it provides basic line editing. On the other hand, arrow keys don’t work, the calculator is not programmable, you can’t control the output format, there’s no undo support, trigonometry is always in radians, there’s no support for complex numbers, and the standard library is somewhat impoverished (e.g., pick is not yet implemented). All of these will be fixed before we declare version 1.0; if you’d like to help, please get in touch!

EC’s input language is not yet stable. At some point before version 1.0 is declared, the input language will become stable, but for the time being, any scripts you write in the EC language may be broken by future releases. If you’d like to take on any serious scripting in EC, please get in touch; we may be able to provisionally stabilize certain language features to avoid breaking you.

Currently, EC performs all computations with double-precision binary floats. This means that all the ordinary issues with binary floating point come into play; notably, many common decimal fractions (like 0.1) cannot be represented exactly within EC. EC uses guard digits and conservative display settings to prevent the most obvious roundoff errors (EC displays 0.1 as 0.1, not 0.10000000000000000555), and all told, EC’s precision is fairly close to that of the original HP calculator line. Nonetheless, EC does not yet offer the same level of precision as more recent calculators (e.g., the HP Prime) or true computer mathematics systems (e.g., Xcas). If you’re doing heavy-duty numerical analysis, EC is not yet the tool for you.

To build EC, you’ll need our customized version of Abseil, which is checked in as a Git submodule. You’ll also need GCC, Antlr 4, and Ninja, none of which is checked in; on a Debian system, you can run apt install build-essential ninja-build antlr4 libantlr4-runtime-dev to get the packages you need. Fire up ninja, wait a bit, and you’ll soon have an ec binary in the repository root. Enjoy!