Command Editor

The Command Editor is a REPL — type a command, the active interpreter evaluates it, the result comes back. Same shape as a Python or R prompt, but with a cross-language twist.

Picking the interpreter

A combo-box at the top of the Command Editor lets you select which interpreter handles the next command. Available choices:

• MathJet’s built-in interpreter — always available; MATLAB-syntax compatible.
• External language installations — Octave, Python, R, and others detected on the system. MathJet probes for supported installations every time a session starts and updates the combo-box list automatically.

When the built-in interpreter is selected, a second combo-box becomes available for picking the language syntax. The built-in interpreter understands multiple syntaxes and switches between them dynamically based on the selection. This is how the polyglot formula bar works under the hood — see Coming from MATLAB for the user-level pitch.

When an external installation is selected, the syntax combo-box is disabled — only the language supported by that installation is available.

Working in the editor

Standard REPL behaviors:

• Press Return to submit the current line.
• Multi-line statements (function definitions, control-flow blocks) are recognized automatically; submission waits until the block is complete.
• Output from the interpreter appears below the input.
• The same Edit → Find / Ctrl+F behavior as everywhere else in the GUI works in the Command Editor (see Find and Replace).

Statements run from the Command Editor are logged in the Command Recorder window for replay, reverse-execution, and persistence across sessions.

See also

• Command Recorder — logged history of every statement, with reverse-execution support.
• Environment Window — values produced by Command Editor statements appear here as they enter the interpreter’s evaluation stack.
• Debug Windows — for stepping through scripts rather than line-by-line REPL evaluation.