j901 app for iPhone and iPad

J is a general purpose programming language inspired by APL, both languages springing from the fertile mind of the late Ken Iverson. J is particularly strong in the mathematical, statistical, and logical analysis of textual and numerical data.

j901 is the follow-on product of j701. This version of the J Integrated Development Environment (J IDE) employs version 9.3 of the J Engine.

How J901 differs from J701:
* Abandons special keyboard for custom keys on system keyboard
* Session log display, whole or part, e.g. inputs-only; or transactions containing a given J primitive or substring
* Code editor, with tabs and find facility
* Shell-type preprocessor for common housekeeping actions upon jscripts and other files
* Separate scenes for displaying the output from "plot" and "viewmat"
* Context-sensitive Help; NuVoc lookup
* New "Mill" feature for studying noun transformations, e.g. numeric arrays and animated character-graphics such as Conways Game Of Life

Like all J IDEs, this iOS app is offered free of charge as a learning resource for teachers and students of mathematics, statistics, science and engineering. It is also offered without guarantee as a convenience to J experts who normally use a desktop computer for their professional work. Fine-tuned to the iPad, but usable on iPhone, it is first and foremost a vehicle for fun and discovery.

DO NOT USE FOR MISSION-CRITICAL WORK – iOS end-user security trumps app recovery.