Rpn28xcalc

Rpn28xcalc is a programmable scientific calculator designed for both iPhone and iPad, operating on iOS or iPadOS version 11 or later. It employs reverse-polish notation (RPN) for calculations and features a dynamic, interactive stack display that allows users to scroll, reorder, and modify stack entries. The calculator is tailored for users requiring high-precision arithmetic, supporting numbers with up to 38 significant digits.

The app accommodates a wide range of data types, including real and complex numbers, binary integers, lists, arrays or vectors, matrices, names, strings, and user-defined programs. Users can write their own programs using a rich command set and assign them to custom buttons for quick access. The command interface is organized into pages, navigable by swiping across button panels, and advanced commands are accessible through secondary panels on iPad or by replacing the regular panel on iPhone. Custom button layouts and reordering are also supported.

Rpn28xcalc includes a catalogue of 147 predefined scientific units and constants, with the ability to add custom units via variables. All units, including Imperial and custom-defined ones, are derived from the seven SI base units, plus an eighth user-defined base unit. Units can be combined, converted if compatible, and scaled using SI prefixes. The assistant window allows browsing of scientific units and variables, editing variables, and creating buttons for program execution. The app provides a command and results history log, from which users can restore previous stacks, retrieve recent operands or commands, and share or edit the log.

The user interface supports both light and dark modes (with dark mode requiring iOS/iPadOS 13 or later) and offers two color themes. On iPad, the app supports multitasking features such as Slide Over and Split View, and the stack display automatically expands as more values are added. Landscape orientation is supported on all devices. Rpn28xcalc is available for $6.99 and contains no ads or rating requests. A downloadable user guide with an introduction and command reference is accessible from within the app.