# Expression cannot begin with "$\sum_{j=0}^{\floor*\frac{a}{b}} j$"

This is my first time using Wolfram Mathematica and writing in TeX. I'm on the free trial version of Mathematica, and I'm writing in a notebook, using the "Inline TeX Input" option on the "Insert" tab. Previously, I have only ever written mathematics in MathJax.

I tried the above first without the dollar signs.

It didn't work then either. I figured maybe the problem was the lack of dollar signs. It appears not. A further confusing detail here is that the slash in front of the sum is red in the last picture, whereas it isn't in the one above. So I thought, maybe I have to add a dollar sign in front of all of them (not that that makes any sense to me, but I have no idea what I'm doing).

It still didn't work, but in this instance, the slashes aren't red anymore. I don't understand why this isn't working, according to this guide, sigma functions are displayed by writing "\sum".

EDIT:

I tried doing as instructed in the answer by @Nasser, but upon pressing enter, the box turned red. Here's the code:

 Failure["TeXAssistantError", Association[
"MessageTemplate" -> "Errors: Errors",
"MessageParameters" -> Association["Errors" -> {}],
"Input" -> "crtl$\\sum_{j=0}^{3} j"]]  • People here generally like users to post code as Mathematica code instead of just images or TeX, so they can copy-paste it. It makes it convenient for them and more likely you will get someone to help you. You may find the meta Q&A, How to copy code from Mathematica so it looks good on this site, helpful Oct 27, 2021 at 23:46 • @MichaelE2 Thank you, I will do so :) Oct 27, 2021 at 23:59 ## 1 Answer You have to first type ctrl$ then type the LATEX there with no $'s, since it is implied math mode. like this Which was entered using Then hit the return key. For more info, see InlineTeXInput.html btw, no one really writes * in Latex as multiplication is implied with just the space. Better not use * in Latex. Here is a video. Hitting CTRL$ is just a short cut for using the menu. Both work the same.

• I tried doing this, but it didn't work. I have edited my question to include my faulty code. Not sure how I did it wrong. Oct 28, 2021 at 0:15
• @user110391 Could you post the latex on its own in your question that you are trying to input? as plain text? i.e. type the latex only. It could be your latex is not well formed. do not use double backslash. Only ONE backslash. You type normal latex in the input windows. I just tried it and it worked for me. Oct 28, 2021 at 0:16
• Not sure what typing the latex as plain text means. Does it mean like this: "\sum_{j=0}^{3} j". That is the last expression I tried to put in, when I tried putting the "ctrl\$" in front of it. Oct 28, 2021 at 0:21
• @user110391 You need to first type ctrl with dollar, then this should open a new small window like I showed. Only then you type the Latex there. are you using version 12.3? If you like I can post a video showing how. But first you need to have that little new window open. You do NOT type ctrl with dollar inside the little window that opens up. Only pure latex goes there. Oct 28, 2021 at 0:24
• @user110391 I just tried it. Mathematica does not understand the latex command \floor. Looks like a bug. This is all new stuff and will have bugs in it. So basically try not to use these commands in your Input Latex for now. As for your sigma function solving, I suggest you make separate question on that, not related to Latex at all and keep it all using Mathematica code. Else this is getting confusing to have it all here with the latex issues involved. Oct 28, 2021 at 1:05