I have moved my comments policy, with help entering equations to its own page, accessible from the top bar above.

Recently, a few people have had trouble leaving comments on the site, due to incorrectly formatting equations, and some capricious comment mulilation by the WordPress software.  It took me a little while to figure out the exact rules since apparently the comment box which you would enter text into, has slighly different rules than the ones I enter text into as a logged-in user.

So here's the deal.  WordPress uses < and > to enclose html tags.  For example, if you write "<b>this is bold</b>" in a comment, you'll see "this is bold".  Unfortunately, this means that if you include an < followed by an > in your comment, WordPress will interpret whatever is in between as an html tag, and—even if it is not a valid html tag—will simply delete everything in between them!  Even I will be unable to see what you originally wrote.  So do NOT use > or < to mean greater than or less than (unless you use just one kind, or only >'s followed by <'s... but the safest rule is just to avoid them entirely...).

If you want to include greater than or less than symbols, you can write them as ${\mathrm \\\verb|\|\mathrm{gt}\\}$ or ${\mathrm \\\verb|\|\mathrm{lt}\\}$.  That will look like > or < respectively.  Or better still, put your entire equation inside of the double dollar signs using LaTeX notation.

[quietfanatic points out in a comment below that you can also use the html escapes $\&$gt; or $\&$lt; if you don't want to use the double dollar signs.]

Also, do NOT try to use wordpress.com latex notation (which has a single dollar signs, and the magic word "latex").  It won't work!  There is a difference between wordpress.com and wordpress.org.  The former is a website used to host WordPress blogs, while the latter is where you download software to host your own WordPress blog.  This is a WordPress.org blog which is hosted on my family server, wall.org.

In order to put LaTeX in a wordpress.org blog, you have to install a special plugin to do so.  You might think that this plugin would use the same notation as wordpress.com, but no it doesn't.  Instead you type $\\\mathrm{E = mc\verb|^|2}\\$ to get $E = mc^2$, and type $\\!\mathrm{E = mc\verb|^|2.}\\$ to break it out into a separate line like so:

It's best not to put any spaces after the dollar signs in this case, or they'll make a weird indentation in the next line, as shown here.

Got it?  Good.

I am a postdoctoral researcher studying quantum gravity and black hole thermodynamics at the Institute for Advanced Study in Princeton. Before that, I read Great Books at St. John's College (Santa Fe), got my physics Ph.D. from U Maryland, and did my first postdoc at UC Santa Barbara.
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### 4 Responses to Help with leaving comments

1. quietfanatic says:

Testing the use of HTML escapes &lt; and &gt; to get < and >. $x < y > z$

2. Aron Wall says:

Yes, that would work too. I've put a comment to that effect in the post above.

3. g says:

The comment in the post is (at the time of writing) missing the semicolons after the entity names: it needs to be &lt; and &gt;, not just &lt and &gt (note: I have no idea whether the foregoing will come out right; will post a correction of some kind if not).

[Fixed. Thanks--AW]

4. g says:

(It came out right.)