Negated Operators


Sometimes you need to enter a negated operator like ≠. If you’re a C/C++ programmer, you might think that != should map to ≠, since that’s what != means in those languages (and some others). But since in mathematics ! means factorial, this choice is a bad idea for inputting ≠ into mathematical text. You can type in \ne to get ≠, but there’s the simpler combination: /=. In the linear format used in Microsoft Office math, / is used for “stacked” fractions. But /= building up to a fraction with an empty denominator followed by an equal sign isn’t very useful. Also if you really want such a fraction, you can get it by typing /<space>.


Accordingly in Office 2010 math entry, /= builds up to ≠. This approach can be used to input many other negated operators as listed in the following table


 

















































































































Operator


Negated op


Input


< 



/<


=



/=


> 



/>




/\exists




/\in




/\ni




/\sim




/\simeq




/\cong




/\approx




/\asymp




/\equiv




/\le




/\ge




/\lessgtr




/\gtrless




/\succeq




/\prec




/\succ




/\preceq




/\subset




/\supset




/\subseteq




/\supseteq




/\sqsubseteq




/\sqsupseteq


 


All of these operators are in the U+2200 Unicode block (Mathematical Operators) except for the ASCII characters <, =, and >. TeX has a similar, but more verbose approach that uses the control word \not followed by the name of the operator. For example, in TeX, \not\exists produces ∄.


Note that if you don’t like an automatic translation when entering math, you can undo the translation by typing ctrl+z. This way of entering negated operators along with some other extensions to the linear format will be documented in a future version of Unicode Technical Note #28.


 


Comments (5)

  1. Nali says:

    This new way for inputting negated operators is very useful and easy to use. Thank you for this improvement.

  2. Hermann Klinke says:

    I've found that some automatic translations cannot be undone without losing the entire equation. Instead I use the arrow right keys to avoid automatic translation.

  3. MurrayS says:

    Word, OneNote, and PowerPoint each have their own undo facilities. The automatic translations can be undone with varying granularities. Word seems to have the finest granularity, followed by PowerPoint. I do notice that typing a/=b into a OneNote math zone followed by ctrl+z (undo), in fact, deletes the entire equation. Thanks for the bug report.

  4. Ro says:

    That's great, but what about operators that are not in your list? The Cambria Math font doesn't contain a symbol for the negated versions of some operators, e.g., the equivalent of the LaTeX leadsto. Is there no way to negate these operators?

  5. MurrayS says:

    Is leadsto the same as U+2933 "wavy arrow pointing directly right"? If so, you can enter it as 2933 alt+x and you can add it to your math autocorrect list as leadsto. To negate it, the first thing that comes to mind is to follow it with U+0338 "combining long solidus overlay", but I tried it and it's not currently supported by the math accent object although it should be. Thanks for the question.