Missing $ inserted underscore sign - latex

Here is my snippet from LaTeX doc i am creating:
54 \subsection{Definicja}
55 Interpolacją nazywamy czynności, których celem jest znalezienie wartości pewnej
funkcji \textit{f(x)} w dowolnie wybranym punkcie z przedziału x_{0}, x_{n}
I keep getting error:
konstrukcja.tex:55 Missing $ inserted ...dowolnie wybranym punkcie z przedziału x_
I am new to LaTeX so I have no idea what does it mean.

Wrap mathematical expressions in $...$. Since you did not know that it is best for you to read a basic introduction to LaTeX. There are a lot of references listed in these two questions on TeX.SX:
What are good learning resources for a LaTeX beginner?
LaTeX Introductions in languages other than English
My personal favourite is »LaTeX and friends« by M. van Dongen.
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\begin{document}
\subsection{Definicja}
Interpolacją nazywamy czynności, których celem jest znalezienie wartości pewnej
funkcji $f(x)$ w dowolnie wybranym punkcie z przedziału $x_{0}$, $x_{n}$
\end{document}

"Missing $ inserted" is probably caused by the underscores
Try:
przedziału x\_{0}, x\_{n}

Related

Mixing text and equations in latex

I am working on some algorithm documenation for a project and trying to write out the equations in latex.
The one problem I am encountering and have not found a nice way (assuming there is one) is mixing text and equations in a single line.
Here is an example of what I am doing (and later how I am doing it).
I am defining the equation, and than what each variable means (left aligned text hence the &).
The latex code to generate this
\begin{equation}
A = 3B * 4C + 5D
\end{equation}
Where:
\begin{flalign*}
&A = Something \: cool\\
&B = Something \: cooler\\
&C = Something \: even \: cooler!!\\
\end{flalign*}
My questions are:
Is there a better way to do spaces in between words besides putting \: everywhere?
If I dont put the \: I get this below, all the words are combined?
Is this the most latex idiomatic way to acheive this? Am I missing something that could help me?
So I can get the output the way I want, I just want to make sure its "correct" before I get to deep.
You should never set whole words in math mode. Besides the obvious problem with spaces you noticed, this will also completely mess up the kerning between the letters.
Instead you can use the \text{...} macro from the amsmath package.
The amsmath package also provides the \intertext macro, which you could use to insert Where: while retaining alignment of the equal signs in the equations above and below:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{flalign}
A &= 3B \cdot 4C + 5D\\
\intertext{Where:}
A &= \text{Something cool}\notag\\
B &= \text{Something cooler}\notag\\
C &= \text{Something even cooler!!}\notag
\end{flalign}
\end{document}

LaTex how to edit this equation?

I'm having issues turning this word equation into a LaTex equation. It's coming out looking dodgy, please help!
I added a screen shot of the equation I want, and what I end up getting when I copy and paste into LaTex:
WORD:
LATEX CODE:
\mathrm{=\ }\mathrm{C}_\mathrm{0}\mathrm{[1-}6(Dt)1/2aπ2-3Dta2] + 12(Dt)1/2an = 1∞exp(na(Dt)1/2)
and therefore nothing comes out and LaTex doesn't let me run it.
This is absolutely not a proper LaTeX equation code. I don't know what you know about LaTeX, but you cannot just copy and paste from Word or any software to you LaTex editor. Plus, you need to provide your full code for anyone being able to help you.
Anyway, running this MWE should work :
\documentclass[11pt, a4paper, twoside]{report}
% ===== PACKAGES DECLARATION =====
\usepackage{mathtools} % Replaces amsmaths + more features
\usepackage{amsfonts} % Maths fonts package
% ===== DOCUMENT BODY =====
\begin{document}
\begin{equation} % optional : use the "equation*" environment to remove equation number
% optional : use traditional math font by removing the \mathrm{} command
\mathrm{X = C_0 \left[ 1 - \frac{6(Dt)^{1/2}}{a \pi^2} - \frac{3Dt}{a^2}\right] + \frac{12(Dt)^{1/2}}{a} \sum_{n=1}^\infty \exp\left(\frac{na}{(Dt)^{1/2}} \right)}
% optional : remove auto-sized brackets by removing the \left and \right commands
\end{equation}
\end{document}
As written in the code, you may want to remove the equation number and the big auto-sized brackets (that are more readable in my opinion). Just remove the corresponding commands. Also, you should consider using the "normal" math font and not the roman one that is clearly different from the text and helps the reader to separate equations from inline small expressions you could insert in your document.
One first sketch:
\documentclass{article}
\begin{document}
\[
C_0\left[1-\frac{6(Dt)^{\frac{1}{2}}}{a\pi^2}-\frac{3Dt}{a^2}\right]+%
\frac{12(Dt)^{\frac{1}{2}}}{a}\sum^{\infty}_{n=1}%
\exp\left(\frac{na}{(Dt)^{\frac{1}{2}}}\right)
\]
\end{document}
No packages required. The output:
Than you can tune the math fonts and anything else.

How to implement full LaTeX syntax in Rmarkdown?

I have a two part question regarding the use of LaTeX in Rmarkdown:
1) When working in Rmarkdown (with the intent to render to PDF), is there a rule for when we should just use the double dollar signs ($$) to write something in LaTeX or when we should use the LaTeX syntax to begin and end all of our LaTeX code (e.g. \documentclass{...}, \begin{document}, \end{document}, etc.
I believe I have read that it is okay to just use the latter option, and Rmarkdown will ignore all of the escaped latex commands if the document is rendered to anything other than PDF.
2) The reason I am asking, in this case, is that I am trying to incorporate some labelled matrix multiplication in an Rmarkdown document I am writing. Specifically, I would like to include some matrices that take the form show on this page. Here is the code:
\documentclass{article}
\usepackage{amsmath}
\newenvironment{spmatrix}[1]
{\def\mysubscript{#1}\mathop\bgroup\begin{pmatrix}}
{\end{pmatrix}\egroup_{\textstyle\mathstrut\mysubscript}}
\begin{document}
\begin{equation}
\begin{spmatrix}{A}
a & b \\
c & d
\end{spmatrix}
\begin{spmatrix}{x}
x_1 \\
x_2
\end{spmatrix}
=
\begin{spmatrix}{b}
b_1 \\
b_2
\end{spmatrix}
\end{equation}
\end{document}
How would one implement this code in Rmarkdown? Do you need to move the \usepackage call into the YAML as suggested in other threads discussing the loading of LaTeX packages in Rmarkdown? Is the first line, \documentclass{article} even needed within an Rmarkdown document?
I'm new to all of this, and thusfar, I've been able to get by using the double dollar signs to set off all my LaTeX code for simple equations and even a simple matrix here and there that I've tried to write, but for mathematical expressions that require more formatting, aligning, multi-line proofs, etc., most of the examples I've encountered are on the TEX boards written with syntax similar to the code above. I haven't been able to figure out how to implement these types of examples in Rmarkdown. Any helpful suggestions or pointers where to better understand this issue would be much appreciated!
It is indeed possible to put most body-level LaTeX constructs into the body of your Rmd file. Other backends will ignore these constructs, but the result might look change. So from my point of view your are binding yourself to PDF output. But that might be fine in your case.
Concerning your concrete problem:
amsmath is already included by the default template, which also takes care of \ḑocumentclass and the document environment.
You need to add the environment definition into a separate tex file (in my case preamble.tex) and include that file via the YAML headers.
You can then use the LaTeX constructs as is in the Rmd body.
Putting things together:
---
output:
pdf_document:
keep_tex: yes
includes:
in_header: preamble.tex
---
\begin{equation}
\begin{spmatrix}{A}
a & b \\
c & d
\end{spmatrix}
\begin{spmatrix}{x}
x_1 \\
x_2
\end{spmatrix}
=
\begin{spmatrix}{b}
b_1 \\
b_2
\end{spmatrix}
\end{equation}

non-ASCII characters in Julia sourcefiles (e.g. θ) come out mojibake (e.g. Îÿ) using '\lstinputlisting{}' in LaTeX

I would like to include some Julia source in a LaTeX doc. I am familiar with the 'listings' package, and have crafted a decent 'lstdefinelanguage'. But I am having trouble with non-ASCII characters in the jl. I have played around with various 'lstset' and 'inputenc' options like 'extendedchars' and 'utf8' to no avail. I am using TeXShop on a Mac. Has anyone cracked this?
You can use literate option although it requires some set-up work. Here is a MWE:
\documentclass{article}
\usepackage{listings}
\usepackage{courier}
\lstset{basicstyle=\ttfamily}
\lstset{literate=
{δ}{{$\delta$}}1
{ϵ}{{$\epsilon$}}1
}
\begin{document}
\begin{lstlisting}
function f()
ϵϵϵϵϵ = 1
xxxxx = 3
δδδδδ = 2
ϵ + x + δ
end
\end{lstlisting}
\end{document}

Error while writing multi-valued function in LateX

I am creating a document in LateX and the following multivalued function has been giving me trouble for a while.
The Latex code for the above as I gave is
$\[delta \tau_{i,j}^{k}$ = $\left\{$
\begin{array}{l l}
\frac{1}{L_{k}} & \quad \mbox{if ant k travels on edge \textit{i,j}} \\
0 & \quad \mbox{otherwise}
\end{array} \right. \]
While compiling it gives me the following error
! LaTeX Error: Bad math environment delimiter.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.52 $\[
delta \tau_{i,j}^{k}$ = $\left\{$
?
Any help on fixing this error would be much appreciated.
aschepler is right--it's the [ inside the $.
You may also want to consider the cases environment, which I think is easier for this sort of thing. For you example, you'd have:
\[
\Delta\tau_{i,j}^k=
\begin{cases}
1/L_k & \text{if ant $k$ travels along edge $i,j$} \\
0 & \text{otherwise}
\end{cases}
\]
You can't use both $ $ and \[ \] like that. $ is for in-line equations (fit within a paragraph of text), so you should probably use just \[ \] around your equation and remove all the $s.

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