Now I've asked this question here before, but since then I've lost my account, and after an hour of trying to find the answer again somewhere on this site, I thought I'd just ask it again. So it definitely is a duplicate, but I haven't a clue at how to find where this question was asked before. I apologize in advance.  The essential problem is to make your own summation command. The idea would be instead of writing \Omega_{j=1}^n which renders the j=1 to the lower right of Omega and renders the n to the upper right of Omega, I would like to have them indexed beneath and above, respectively. Exactly how the command \sum is rendered, except I don't want a capital sigma, I want a capital omega.  I can't remember how I did it before, and I recently lost the Latex files for a document I wrote using this command incessantly. I'm now in the midst of reconstructing the Latex file from the PDF and I can't for the life of me remember how I made this command.  Any help would be greatly appreciated.
27555
How can i write my own math operator with limits? I want it to look like:  \sum\limits_{e=1}^{m} but with a capital A (if possible bigger than the normal text) instead of the sum.  Thanks for the help!
24281
When searching on a site with  enabled (), I saw some  rendering issues: (and currently it's also in the )        Even though the LaTeX rendering is fine when opening the :        The LaTeX code is:  $f(n) = \begin{cases} 0,  &amp; \text{$ \omega&lt;0, \omega=1, \omega&gt;3 $} \\[2ex] -\omega + 1,  &amp; \text{$ 0\le\omega&lt;1 $} \\[2ex] \omega^2 - 1,  &amp; \text{$ 1&lt; \omega \le 2 $} \\[2ex] 3 \omega,  &amp; \text{$2 &lt; \omega \le 3 $} \end{cases}$
96638
I'm new to LaTeX and I'm trying to figure out how to correctly format a proof. Can someone show me a basic template for how to do this?   The part I am having the most trouble with is creating new columns and customizing alignment... for instance, how do I add a right-aligned annotation (i.e. by distributive property) to a line of this sample proof? Should I use eqnarray* or is there a better option?  \begin{proof}   Let $t,u \in \mathbb{R}$ where $t=xy$ and $u=zw$. So,   \begin{eqnarray*}     4xyzw &amp;=&amp; 2\cdot2tu \\     &amp;\le&amp; 2\cdot(t^2+u^2) \\     &amp;=&amp; 2\cdot((xy)^2+(zw)^2) \\     &amp;=&amp; 2\cdot(x^2y^2+z^2w^2) \\     &amp;=&amp; 2x^2y^2+2z^2w^2 \\     &amp;\le&amp; ((x^2)^2+(y^2)^2)+((z^2)^2)+(w^2)^2) \\     &amp;=&amp; x^4+y^4+z^4+w^4   \end{eqnarray*} \end{proof}
88417
I am stuck with a LaTeX glitch! I am making an exercise on sequences and series. I have to write down an expression for the general form of a sequence for which I need large delimiters. I tried various ways but it did not work.   Here is a minimal example.  \documentclass[a4, 14pt]{extarticle}  \begin{document}  \begin{align}  \[ \left{        \frac{(-1)^{n}}{n}     \right}_{n=1}^{\infty}  \]  \end{align}  \end{document}   I tried $$ .... $$, \[ ... \], and \begin{align} ... \end{align} but all returned errors on compiling. I don't know how to fix this!
90437
Let $\omega$ be a complex number such that $\omega^5 = 1$ and $\omega \neq 1$. Find   $$\frac{\omega}{1 - \omega^2} + \frac{\omega^2}{1 - \omega^4} + \frac{\omega^3}{1 - \omega} + \frac{\omega^4}{1 - \omega^3}.$$   I have tried adding the first two and the second two separately, then adding those sums but how do I get a numerical value as the answer?   Thanks
62357
How can I write e^(3j) in LaTeX?  I have tried many syntax, like $e^(3j)$ or $e^*{3j}$  Any help will be very well received.
29033
The following code does not compile:  \documentclass{article} \usepackage{amsmath} \begin{document}  \begin{align}      \eta_{m} = &amp; \omega_{m1}D_{1} + \omega_{m2}D_{2} + \dots + \omega_{mT}D_{T} \\     \eta_{a} = &amp; \omega_{a1}D_{1} + \omega_{a2}D_{2} + \dots + \omega_{aT}D_{T}  \end{align}  \end{document}   However, if I remove empty lines, it does. (Same with equation environment). Why? Why would it be problematic for a code to allow spaces? Convention?   For reference, the error in TexStudio is quite dramatic, for an apparent trivial issue:  line 7: Paragraph ended before \align was complete. line 7: Missing $ inserted. line 7: Missing \endgroup inserted. line 7: Display math should end with $$. line 8: Misplaced alignment tab character &amp;. &amp; line 8: Missing $ inserted. &amp; \omega line 9: Misplaced alignment tab character &amp;. &amp; line 10: Missing $ inserted. line 11: Misplaced \cr. \end{align} line 11: Misplaced \noalign. \end{align} line 11: Misplaced \noalign. \end{align} line 11: Extra }, or forgotten \endgroup. \end{align} line 11: Missing $ inserted. \end{align} line 11: Display math should end with $$. \end{align}   NOTE: I am aware of , , and  question. But none of them explains why empty lines are problematic (besides a trivial and rather tautological answer like "the code does not allow it").
17009
I am looking for a command that will accept (as input) multiple lines of text, each line containing a single integer, and output the sum of these integers.  As a bit of background, I have a log file which includes timing measurements. Through grepping for the relevant lines and a bit of sed reformatting I can list all of the timings in that file.  I would like to work out the total. I can pipe this intermediate output to any command in order to do the final sum.  I have always used expr in the past, but unless it runs in RPN mode I do not think it is going to cope with this (and even then it would be tricky).  How can I get the summation of integers?
104083
Is there a standard TeX or LaTeX code for a symbol that bears the same relation to  \prec\prec that \ll bears to &lt;&lt; ?  (And how do I get TeX code to get rendered in a question posted here?  I'm accustomed to writing things like $\sum_{n=0}^\infty \frac{x^n}{n!}$ on math.stackexchange.com and having it look the way you'd expect it to.)
24287
The following code:  $\dfrac{\left( \dfrac{\left( \dfrac{1}{2}\right) }{2}\right) }{2}$   gives a nasty output:   It seems that the $\left( \right)$ command doesn't do the job.  Any idea how to solve this in general?
76323
For some lecture script I am preparing I would need some descriptive images showing how to work with spherical coordinates as often seen in textbooks, i.e. a globe and some descriptive arrows annotating \Phi, \Theta, etc.  Can someone tell me if, and how, this can be done in latex (I am a fairly familiar with LaTeX for typesetting text but a novice when it comes to PSTricks and co.)!
95451
\documentclass{article} \begin{document} \begin{equation*} P^*(A) = \begin{cases} 1 &amp; \quad \omega_0 \in A, \\ 0 &amp; \quad \omega_0 \notin A. \end{cases} \end{equation*} \end{document}   When I used the above code to display a piecewise expression, I got the following:    Clearly, the curly brace appeared in the expression is too big, how can I adjust it so the display is more satisfactory? Thanks in advance.  P.S: My preamble:  \usepackage{setspace}  \doublespacing \usepackage[margin = 1.5in]{geometry} \usepackage{float}  \usepackage{graphicx} \usepackage{color}  \usepackage{amsmath}  \usepackage{amsfonts}  \usepackage{amsthm} \usepackage{bm}  \usepackage{framed} \usepackage{verbatim} \usepackage{natbib} %\usepackage[symbol*]{footmisc} \usepackage[stable]{footmisc} \usepackage{mathtools} \usepackage{mathrsfs} \usepackage{amssymb} \usepackage{hyperref}    \newcommand{\eps}{\varepsilon} \newcommand{\rational}{\mathbb{Q}} \newcommand{\real}{\mathbb{R}} \newcommand{\integer}{\mathbb{Z}} \newcommand{\nn}{\mathbb{N}} \newcommand{\complex}{\mathbb{C}} \newcommand{\Ell}{\mathcal{L}} \newcommand{\mean}{\mathbb{E}} \newcommand{\prob}{\mathbb{P}} \newcommand{\dd}{\mathop{}\!\mathrm{d}} \newcommand{\overbar}[1]{\mkern 1.5mu\overline{\mkern-1.5mu#1\mkern1.5mu}\mkern 1.5mu} \DeclareMathOperator*{\argmin}{arg\,min} \DeclareMathOperator*{\diam}{diam\,} \newcommand{\Riemann}{\mathscr{R}}  \theoremstyle{definition} \newtheorem{defn}{Definition}[section] \newtheorem{defns}{Definitions}[section] \newtheorem{exmp}{Example}[section]  \theoremstyle{plain} \newtheorem{thm}{Theorem}[section] \newtheorem{lem}{Lemma} \newtheorem{prop}{Proposition} \newtheorem*{cor}{Corollary}  \theoremstyle{remark} \newtheorem*{rem}{Remark}
64234
A number of related questions have already been asked about this issue:       and even    But I'm still confused by the conflicting suggestions that have been given so far. So I'm trying again.  Which should be the preferred command to produce a displayed equation in my LaTeX documents?  So far the suggestions indicate that one should use \[ ... \], maybe \begin{equation*} ... \end{equation*}, or maybe even the gather* or align* environments from amsmath.  And one should definitely avoid using either $$...$$ or the eqnarray environment.  Now I have to say that, from a language perspective, I have a strong preference for the equation* environment because it is less cryptic than the \[ ... \] notation and it is  the most accurate.  So, is it fine to use equation*? Maybe only after loading amsmath? Or should the equation/equation* environment be redefined to something else so that spacing, package support, or whatever is improved?
2902
I am doing summer project in maths and I have to type my report. I am good with the latex I write on mathstack that I have learned through experience but when it comes to softwares, I do not know anything like those commands \begin \end does not make sense to me.   Is there any software which can automatically put these commands in, so that in b/w we can type whatever stuff we want?  Also if not, at least you guys can tell me if there is any latex software which shows the output on half of screen(right half), as I type on left half and compile, (I saw it somewhere).  Anyways, I have to download a software and will have to go through some you tube videos, so please suggest me relatively easy Latex software.  Thanks!  P.S. Please edit the tags as you wish, I did not understand many tags here.
124264
I have below inputs with huge number of rows  11|ABCD|19900101123123445455|555|AAA|50505050|0000009030 11|ABCD|19900101123123445455|555|AAA|50505050|0000000199 13|ABCD|201803010YYY66666666|600|ETC|20180300|0000084099 11|ABCD|19900101123123445455|555|AAA|50505050|0008995001   And I need to get below output  11|ABCD|19900101123123445455|555|AAA|50505050|9004230 13|ABCD|201803010YYY66666666|600|ETC|20180300|84099   I have been trying with below awk but having too limited knowledge with arrays.  cat test|awk -F"|" '{ a[$1]++;b[$2]++;c[$3]++;d[$4]++;e[$5]++;f[$6]+=$6 }; END { for (i in a); print i, f[i]}'   I need to sum last column of column number 6 and print all first 5 columns, which are separated by pipe and last 6th column as sum of 6th column.
102104
I am writing some proofs using LaTeX, and following the standard procedure in the ConTeXt, I need to write something as follows:    However, I have no idea how to create the "double bracket", like the one includes x := y + z...  Could anyone give me some help on this?
59464
I have a fraction with sums above and under the line. How can I convince LaTeX to write the indices of the sums under the sigma instead of next to it?  \begin{displaymath}   \frac{\sum_{s \in S} s^2}{\sum_{p \in P} p^2} \end{displaymath}