Format for Mathematical Expressions

[daniel314shoe]

TL;DR Summary: Why has format for mathematical expressions changed?

The formula I am using as an example here is from classical physics so that is why I have chosen the classical physics forum. I have been running into a new format very different from what I have been used to for decades. For example the formula for the natural frequency of a pendulum can be expressed as Wn = (m g r/ Ip)^0.5 but now I see this format: [ w = \frac{\mu m g r}{I} \cdot \frac{d}{V_o} . When and why did this change occur. What is the name of the new formatting and where can I get a guide to translate it back to what I am used to?

 

[berkeman]

Are you asking about using LaTeX to post math equations instead of trying to cobble them together with text?

If so, to post math equations, it's best to use the LaTeX engine that PF provides. There is a helpful "LaTeX Guide" link below the Edit window to get you started. Note that you put double-$ delimiters at the start and end of each stand-alone line of LaTeX, and double-# delimiters at the start and end of in-line LaTeX that does not need to be on its own line.

Example of in-line LaTeX: $v(t) = L \frac{di(t)}{dt}$

Example of stand-alone LaTeX:
$$v(t) = L \frac{di(t)}{dt}$$
Also, if you right-click on a LaTeX equation in a post, you get a pop-up menu to let you view the LaTeX source or view it in other formats.

LaTeX isn't supported in thread titles, so you can use simple text math in titles if you want.

Note also that PF uses a feature called "lazy LaTeX rendering" that speeds up page loads. When you first post your LaTeX in a thread, you will not see it rendered that first time. Just refresh your browser page to force it to be rendered, and then it should render whenever you come back to that page/thread in the future.

If you have trouble using the Preview feature to check your LaTeX, you can use a website such as https://www.quicklatex.com/ or https://latexeditor.lagrida.com/ to preview your LaTeX before you post it.

 

[renormalize]

TL;DR Summary: Why has format for mathematical expressions changed?

The formula I am using as an example here is from classical physics so that is why I have chosen the classical physics forum. I have been running into a new format very different from what I have been used to for decades. For example the formula for the natural frequency of a pendulum can be expressed as Wn = (m g r/ Ip)^0.5 but now I see this format: [ w = \frac{\mu m g r}{I} \cdot \frac{d}{V_o} . When and why did this change occur. What is the name of the new formatting and where can I get a guide to translate it back to what I am used to?

Your first formula is written as a simple text expression, and the second is written in teX typesetting code. But the two expressions you show are completely different and neither is the natural frequency of a simple pendulum. The correct formula could be written in "text mode" as wn = (g/L)^0.5, but using LaTex here on PF displays it much more elegantly by writing it in the coded form \omega_{n}=\sqrt{\frac{g}{L}}. If you sandwich this code between two #-symbols before, and two after, PF renders this as $\omega_{n}=\sqrt{\frac{g}{L}}$.

 

[Ibix]

Note that some forums use \[ and \] to delimit LaTeX (I think that's the MathJax default setting, in fact), so if you are often seeing stuff like \[ \frac {1}{2}mv^2 \] on other forums then it suggests the MathJax library isn't working for you. On this forum, as noted above, we use two # marks at each end of the expression to delimit LaTeX. So I see $\frac{1}{2}mv^2$ rendered as nice-looking maths. Do you @daniel314shoe? Or do you see \frac{1}{2}mv^2 with two # characters before and after it?

 

[Vanadium 50]

I have been running into a new format very different from what I have been used to for decades

But you joined Monday. I am puzzled.

 

[Mark44]

The formula I am using as an example here is from classical physics so that is why I have chosen the classical physics forum.

Your question is really about the formatting of formulas and mathematical expressions, so I have moved your post to the Feedback forum section.

I have been running into a new format very different from what I have been used to for decades.

Apparently what you have been using for decades is plain old text formatting. The Physics Forums site supports a variant of Donald Knuth's TeX typesetting format, commonly known as LaTeX. What we actually use is MathJaX. I don't know how long this has been around, but I believe we've been using it for at least 10 years.

For example the formula for the natural frequency of a pendulum can be expressed as Wn = (m g r/ Ip)^0.5 but now I see this format: [ w = \frac{\mu m g r}{I} \cdot \frac{d}{V_o} .

As already mentioned by another poster, the first form is plain old text formatting. Your second form is incomplete but uses LaTeX markup.
Correctly written is the form used by this site, it would be
$w = \frac{\mu m g r}{I} \cdot \frac{d}{V_o}$


The browser renders, or translates, what was written into what you see above. Unrendered, this would be
##w = \frac{\mu m g r}{I} \cdot \frac{d}{V_o}##

When and why did this change occur. What is the name of the new formatting and where can I get a guide to translate it back to what I am used to?

I don't know how long this has been around, but I believe we've been using it for at least 10 years. I don't know why you would want to translate nicely formatted formulas, like what you would see in textbooks, into ugly text. Rather than translating LaTeX markup into stuff like KE = 1/2 mv^2, it would be better to learn at least the basics of how to use LaTeX. We have a link at the lower left corner of the input pane titled LaTeX Guide. You can learn the basics of it in just a few minutes.

 

[jtbell]

I have been running into a new format very different from what I have been used to for decades.

You haven't been here on Physics Forums for decades, so I suspect you mean that you have been using "plain text format" for decades on various other forums or sites, and are now encountering LaTeX formatting for the first time here. Am I correct?

 

[bob012345]

It’s not that hard and you will get used to it quickly. Also note that you can borrow formatted expressions from your own or other posts if you need to or even source pages of Wikipedia if you need to for complex expressions. No need to type everything from scratch.