This really is an excellent forum. I turn 70 this month and have decided to go back and re-take mathematics courses I originally took 50 years ago. When I hit a difficult concept I turn to MHF and always find help from the regular contributors here.

I am not the definitive expert on using LaTex on MHF. But, when I do use it, it seems I'm always digging around to find out how to express an equation in LaTex like all the "regular" users. There is a lot of confusing information in the forum and some causes a lot of problems. Hopefully, this post will be a one-stop location for people like me who just want to know how to display equations in MHF like all the regulars.

First, CODECOGS is really making it hard to read many of the earlier posts in MHF. CODECOGS is a LaTex interpreter that charges license fees for its use. For whatever reason, that license is no longer in effect and all CODECOGS equations are now replaced with a big error message. The CODECOGS interpreter was invoked with "[ tex] and [ \tex]" or [ math] and [ \math]" delimiters. (I had to insert spaces after the left bracket so you could see the actual command.THESE DO NOT WORK AT THIS WRITINGbut may someday work again if MHF resolves this licensing issue.

What does work? Using dollar-signs ($ -but not bolded) as delimiters with LaTex commands. So,$x^2$appears as $x^2$.

But before you try using LaTex commands, here's some useful information:

- After typing LaTex commands in "Your Message" area (see the green bar at the top of the frame) you have to scroll to the bottom of that frame and click on the "Preview Post" button in the lower right corner. Your message with LaTex interpreted equations will appear
"Your Message" in the "Preview" frame. If you entered your equations according to LaTex rules, your equations will appear in that beautiful notation you see in all the posts by others on this site.above- You can (and should) preview your message multiple times as you enter it to make sure you haven't made a mistake that screws up your equations.
- Spacing doesn't matter in your equation entry. It's helpful to see what you've entered in the message area but LaTex throws away all your spaces when it interprets your equations. If you want spaces in the interpreted equations, you need to use special LaTex spacing commands.
- A definitive list of LaTex commands can be found at "The Comprehensive LATEX Symbol List" by Scott Pakin (19 Jan 17):
http://tug.ctan.org/info/symbols/com...symbols-a4.pdf- A shorter reference guide to the most commonly used LaTex commands can be found at "List of LaTeX mathematical symbols", The OEIS Foundation, (23 JUL 17):
https://oeis.org/wiki/List_of_LaTeX_...atical_symbols- It's a good idea to download these documents so you can use the pdf "Find" function.
- If you don't already know them, familiarize yourself with the keyboard characters that represent math functions: +, -, /, *, ^, etc. You use these in LaTex equations.

OK, so let's hit a quick example. I'm going to use a bold "$" instead of the un-bolded dollar-sign so you can see the equation in plain text and LaTex at the same time. But remember, onlydollar-signs work.UN-BOLDED

Here's a basic equation that demonstrates fractions, powers, square roots and extra spacing (\ ):

$f(x) = \frac {x^3\ -\ 1}{\sqrt{x^4\ -\ 3x\ +\ 16}}$

gives you

$ f(x) = \frac {x^3\ -\ 1}{\sqrt{x^4\ -\ 3x\ +\ 16}} $

Notice that many LaTex commands use brackets "{}" to delimit the parts of operators like sqrt and frac.

I hope this helps others like me who have struggled to learn and remember how to use LaTex on MHF. Enjoy!