What is the character obtained with they key sequence Esc,Esc called? On my front end it is not displayed, but there's something there messing up my input. It's a bit annoying when I'm after a $\mu$ but hit the wrong key.
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2 Answers
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It's what's called an \[InvisibleComma]. It's useful for those times where you don't want a comma to appear, but you still need it, e.g. "a[[p\[InvisibleComma]q]]" for a matrix entry.
The third entry uses an \[InvisibleComma] in between the matrix indices.
answered Feb 7, 2012 at 1:07
J. M.'s missing motivation♦J. M.'s missing motivation
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The next time you wonder what a symbol is you can at least partially answer it yourself by entering it in a string wrapped in FullForm:
(this is just before pressing Esc the second time). You would get:
"\[InvisibleComma]"
Which is surely helpful in some way. You can also get the help page for the character by entering it directly into the help search box:
answered Feb 7, 2012 at 4:51
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3$\begingroup$ Or just enter the original input described (Esc,Esc), select the cell, and look at its underlying expression -- on Mac, Shift+Cmd+E. $\endgroup$– murrayCommented Feb 8, 2012 at 20:28
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$\begingroup$ @murray good suggestion, though I think the Box structure is a little confusing to a new user. $\endgroup$ Commented Feb 8, 2012 at 21:35
{a, b, c}is fine,{a\[InvisibleComma] b\[InvisibleComma] c}is fine, but{a\[InvisibleComma] b, c}isn't. Very peculiar... $\endgroup$