# Going backwards in elementary Latex

• LaTeX
• epenguin
In summary: I still use a pen and paper a lot, but nowadays I use LaTeX and MathJax.MathJax does not load by default unless there is LaTeX on the page already. This is solved if you refresh the page after writing the equations.Thank you. It seems to work now, though there are still some mysteries.Thank you for your input.

#### epenguin

Homework Helper
Gold Member
TL;DR Summary
Can't do fractions
I am trying to help a student but then I need it myself. Spending all my time writing a simple formula in this hateful Latex which ought to be a thing of the past. Not succeeding in writing the formula, to understand what was going wrong I tried the simplest expressions of the kind for fractions which I could write X/x or y/x

$$\frac {X}{x}$$

## \frac {y}{x} ##

That, on my screen, is not working. What I write is what I get. Simple and basic, I am baffled – am I doing something really stupid?

Oh.
Here it works!
but look up the thread "

### About the binding of O2 to Hemoglobin molecules​

on the chemistry forum. Same thing not working it seems to me.

epenguin said:
TL;DR Summary: Can't do fractions

I am trying to help a student but then I need it myself. Spending all my time writing a simple formula in this hateful Latex which ought to be a thing of the past. Not succeeding in writing the formula, to understand what was going wrong I tried the simplest expressions of the kind for fractions which I could write X/x or y/x

$$\frac {X}{x}$$

## \frac {y}{x} ##

That, on my screen, is not working. What I write is what I get. Simple and basic, I am baffled – am I doing something really stupid?
Looks OK to me. Try refreshing your browser page?

epenguin said:
TL;DR Summary: Can't do fractions

I am trying to help a student but then I need it myself. Spending all my time writing a simple formula in this hateful Latex which ought to be a thing of the past. Not succeeding in writing the formula, to understand what was going wrong I tried the simplest expressions of the kind for fractions which I could write X/x or y/x

$$\frac {X}{x}$$

## \frac {y}{x} ##

That, on my screen, is not working. What I write is what I get. Simple and basic, I am baffled – am I doing something really stupid?

Oh.
Here it works!
but look up the thread "

### About the binding of O2 to Hemoglobin molecules​

on the chemistry forum. Same thing not working it seems to me.
MathJax does not load by default unless there is LaTeX on the page already. This is solved if you refresh the page after writing the equations.

berkeman
Thank you. It seems to work now, though there are still some mysteries. Never ran into this problem before.

berkeman
epenguin said:
this hateful Latex
Nah, you need to make friends and get used to it. Maybe the two of you should have intercourse more often.
epenguin said:
which ought to be a thing of the past.
There are good reasons why it's been so long-lived.

SammyS
x y+1
##x^{2}+1##
Just attempts of mine. I appreciate the beauty and clarity of the LaTex result, but isn't it a bit much if a student comes here to ask for help and the first thing he is told is to learn a new language!? You say they will have to learn it sooner or later? I don't think so, I think in a few years time surely this non-wysiwyg pain will have been replaced by an app that interprets handwriting, and so not even the minority that goes on as far as a doctorate will need to know.

In fact I have been using one sometimes. didn't really save me any time but I found it less objectionable. but I was never able to write a matrix or determinant with it - even Σ between limits or a binomial coefficient were hard to do. It would have wasted more students' time and was never good enough for me to recommend to students or to Greg to promote. If it had been probably somebody else would have done so first.

I think the app was an ancestor of something now called MathKey which I find works even less well. I found it totally lacking in instructions, and stultifying and can't do a thing with it.

epenguin said:
[...] isn't it a bit much if a student comes here to ask for help and the first thing he is told is to learn a new language!?
He doesn't have to learn it all at once. The basic notes in the PF latex instructions cover many simple situations. I learned latex simply by collaboratively-editing someone else's document. I.e., learn-by-doing.

The benefit of writing math neatly on PF is that more people are likely to feel like helping -- I hate trying to decipher a ratty photo of someone's bad hand writing.

epenguin said:
You say they will have to learn it sooner or later?
No -- I say that learning small amounts of it gradually will be useful now. Just learn what bits you need at each task.

epenguin said:
I don't think so, I think in a few years time surely this non-wysiwyg pain

epenguin said:
will have been replaced by an app that interprets handwriting,
In all my serious math work these days, I almost never use hand writing. I just type in latex immediately. It's easy enough once one gets used to it. There are many repeated patterns.

epenguin said:
and so not even the minority that goes on as far as a doctorate will need to know.
I wish I could make sizeable wager with you that this won't happen in our lifetimes.

epenguin said:
[...] didn't really save me any time [...]
I find that typing in latex as the first step does save me time. There's no need to re-type it later from hand writing, and there's FAR fewer copying errors from one line to the next since I can just copy-and-paste, then edit.

Wait, wait, wait...

You don't have to "learn" the LaTex language to use a little bit of LaTex. I use it on this forum, but I still don't know it, and probably never will. I learn and use what I need, when I need it. The documentation is good, and most of it you'll never need anyway. Practical LaTex is easier to learn than the physics question you're probably asking about.

Also, from the other perspective, if you are trying to get me to skip over reading your post, you'll want to format it badly. I am way more interested in answering technical questions than I am in solving word puzzles or cryptograms. How much effort the OP puts into their question (and responses) has a significant effect on my desire to get involved.

strangerep said:

IDNUWYM

strangerep

## 1. How do I undo a command in Latex?

To undo a command in Latex, you can use the \reversemarginpar command. This will reverse the changes made by the previous command, essentially "going backwards" in terms of the document's layout.

## 2. Can I go back to a specific point in my document?

Yes, you can use the \label and \ref commands to create and refer to a specific label in your document. This allows you to easily go back to a specific point in your document, even if it is further back than your most recent command.

## 3. Will going backwards in Latex change my previous formatting?

No, going backwards in Latex using the \reversemarginpar command will only reverse the changes made by the previous command. It will not affect any previous formatting or content in your document.

## 4. How can I go back multiple steps in Latex?

If you need to go back more than one step in your document, you can use the \renewcommand{\reversemarginpar}{\reversemarginpar} command multiple times. This will reverse the changes made by multiple previous commands, essentially taking you back multiple steps in your document.

## 5. Is there a way to go back to the beginning of my document?

Yes, you can use the \reversemarginpar command with a negative number as its argument to go back to the beginning of your document. For example, \reversemarginpar{-100} will take you back to the beginning of your document, regardless of how many steps you have taken forward.