Calcula Active

A keyboard-driven, Symja-powered symbolic calculator in the spirit of Emacs Calc — a native JavaFX interface for algebra, calculus, typeset mathematics, and interactive plots.

Year: 2026
Built with: Java 25, JavaFX 26, Symja
Source: github.com/adriandeleon/Calcula

The Calcula workspace showing typeset symbolic expressions, interactive plots, the calculation trail, and the function browser.

Calcula is a keyboard-driven desktop interface around the Symja computer algebra system. It treats the stack as a document rather than a numeric display and supports both RPN and algebraic input over the same command system, with a trail, undo, prefix key chords, and real two-dimensional mathematical layout.

Symja does the mathematics

Calcula is not itself a computer algebra system: Symja does the mathematical heavy lifting. Symbolic evaluation, simplification, differentiation, integration, equation solving, factoring, expansion, and the broader catalogue of mathematical functions come from Symja.

Calcula’s work is primarily the application around that engine: keyboard-first input, the stack and document model, commands and keymaps, typeset rendering, subexpression selection, interactive plots, exports, files, themes, and native desktop packaging. A small toolkit-free core provides expressions and basic exact arithmetic so the application can still open without the CAS, but its symbolic power comes from Symja.

Rendered formulas retain their expression structure. You can select a subterm, navigate through its tree, and run the same registered rewrite commands used by the keyboard, command palette, menus, and contextual actions.

Mathematics as a native desktop document

Most of Calcula’s own work is in presenting that engine as a native desktop document. Stack values render as built-up fractions, radicals, scripts, matrices, and plots rather than plain strings. Interactive curves are compiled to numeric closures for responsive dragging, while Symja supplies exact poles and turning-point labels when it can.

The document exports to TeX, MathML, Typst, PDF, and the system clipboard. Native installers are produced with jlink and jpackage for Linux, macOS, and Windows.