2
\$\begingroup\$

I've often seen a notation where there is a horizontal bar over a letter to indicate the inverted value of something, e.g. q and (not)q for the outputs of a flip-flop. The not q would be a q with a bar over it.

More recently I was trying to describe the inputs to a 16 bit ADC, where one of the lines was R/(not)C.

I just waded through page after page of Unicode but could not find Roman letters with bars over them, except a few vowels.

Is there a way to do that in a Stack Exchange post?

| |
\$\endgroup\$
6
\$\begingroup\$

You mean like \$\overline{this}\$?

Just invoke the \overline command in MathJax:

You mean like \$\overline{this}\$?

To have it not italicized you can use \text{} like in \$\overline{\text{this}}\$.

\$\overline{\text{this}}\$
| |
\$\endgroup\$
  • \$\begingroup\$ Cool. That's exactly what I mean. (voted.) Will that work on other Stack Exchange sites like Stack Overflow or the Arduino SO Beta? What kind of markup is that? \$\endgroup\$ – Duncan C Sep 1 '14 at 18:56
  • \$\begingroup\$ I think it's pretty universal across all SE sites. It's called "MathJax", and it's based on LaTeX. There's plenty of documentation in the SE help and on the web in general. \$\endgroup\$ – Dave Tweed Sep 1 '14 at 19:52
  • 1
    \$\begingroup\$ @DaveTweed since the engine is quite heavy, I think it only works here, on math and perhaps physics \$\endgroup\$ – clabacchio Sep 1 '14 at 21:28
  • \$\begingroup\$ meta.stackexchange.com/questions/128228/… \$\endgroup\$ – clabacchio Sep 1 '14 at 21:39
  • \$\begingroup\$ @clabacchio: After reading through that thread, and a few others linked to it, it would seem that there's more than just a few SE sites that currently have MathJax enabled. I guess we'd need to talk to an SE employee to get a definitive list. \$\endgroup\$ – Dave Tweed Sep 1 '14 at 22:01
  • \$\begingroup\$ I tried it and it doesn't work on the Arduino SE site. Pity. I posted a feature request on the Arduino Meta SE asking for a way to enter this notation somehow. MathJax seems like a decent option. \$\endgroup\$ – Duncan C Sep 2 '14 at 1:33
  • \$\begingroup\$ It doesn't really matter all that much. There are many commonly-understood ways to denote an active-low signal, including /SIGNAL, SIGNAL- and SIGNAL_L. Just pick one and go with it. \$\endgroup\$ – Dave Tweed Sep 2 '14 at 3:47
  • \$\begingroup\$ There's a community maintained list of sites with MathJax support here: meta.stackexchange.com/questions/216606/… \$\endgroup\$ – PeterJ Sep 2 '14 at 10:31
  • \$\begingroup\$ @DuncanC - It greatly reduces pageload speed, so unless there is a major need they try to avoid it. Just for a not in logic would not be reasonable. \$\endgroup\$ – Kortuk Sep 2 '14 at 15:51
  • 1
    \$\begingroup\$ I've added the non-italicized version, I hope you don't mind ;) \$\endgroup\$ – clabacchio Oct 8 '14 at 8:03

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .