Bug introduced in 8.0 and persisting through 10.3.0

It appears that in debug mode, the \[Piecewise] symbol and its associated grid give a syntax error. For a minimal reproduction, enable the debugger, and type in the front end:

Esc pw Esc

Ctrl-Enter (or Ctrl-Return)


Note that the grid must be typed using the keyboard. Inserting it using the menu does not trigger the bug.


Is it a bug? Are there ways to fix that except write it in the input form?

  • 1
    $\begingroup$ I get the same error message on Win 64-bit 10.0.1. $\endgroup$ – DumpsterDoofus Jan 9 '15 at 17:36
  • $\begingroup$ Still there in M10.1.0. $\endgroup$ – Szabolcs Apr 2 '15 at 2:42
  • $\begingroup$ It was introduced in version 8. I never use the 2-d input, but I did in this case, and could not reproduce your observations at first. The problem actually comes from the grid and not from the piecewise bracket itself. I didn't observe the problem on the first attempt because I used the menu to insert the grid (not remembering its keystroke, as I don't use this normally). Only when I used Ctrl-Enter to insert the grid did I see the problem. $\endgroup$ – Oleksandr R. Oct 25 '15 at 2:43

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