Possible Duplicate:          Is there any reason why I should use equation when I align seems to produce the same output?  The reason I am asking is that I like solving math using LaTeX. Sometimes I write a single equation using the equation environment, but later realise I need to include more equations aligned to the first in that same environment. Then I need to change the   \begin{equation} \end{equation}   to   \begin{align} \end{align}   and include the &amp;s as appropriate.  I am thinking then: why not always use align, maybe even including the &amp; before the equal sign, just in case I need to include more stuff there later? If they behave the same, and one is more flexible, why use the other at all? Or are there differences and reasons why I should avoid using align when there is a single equation?
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I always use align in my documents, and avoid equation. Is there anything wrong with that? My reasoning behind this: align > equation, so why not use it?
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I would like to have two displayed equations, broken by a short paragraph, but with aligned equal signs (as if using the align environment).  Is there some way to "break" the align environment temporarily?
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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?
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In general, in most places, it is said that using TeX defaults is the best. However, TeX does provide things like \, and \quad etc. When one should use them? Both in general and in math mode in particular.
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I want to write an equation in latex like the following one.   But I can not align a set of numbers with the coefficients completely. Here's my code:  \begin{equation} \begin{aligned} LNEP = &amp; -0.23LNEER &amp; +1.21LNCOST &amp; +1.50LNFD &amp; -1.03LNCP &amp; -9.44 \\ &amp; (0.12) &amp; (0.13) &amp; (0.27) &amp; (0.37) &amp; (1.33) \end{aligned} \end{equation}   And it looks like this:   Could somebody help me pls? Many thanks.
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I want to be able to  write the following in LaTeX      We make the further assumption that \begin{equation} \label{eqn:assumption} There is a bounded linear operator     $B:X\to X^*$ such that $B^*=B$ and the operator $JB$ is an extension of $T'(0)$\end{equation}   and get a nice output, in such a way that this whole chunk of text along with the math can be referenced later. Of course I can write text inside the equation environment using \text{}, but when I tried this the spacing was all wrong. Can anyone suggest a solution to this?
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--Revised-- I am looking at a math workbook for teenagers. This one has the following structure:  1.Main Chapter 1.1 Subchapter 1.11 Task 1 a) problem 1   b) problem 2   c) problem 3 d) problem 4   e) problem 5 1.12 Task 2 etc. ...  Many of the math problems are very small and the natural thing would be to have them on line, horizontally. However an expression is often broken and aligned at the equal sign. Not unlike an equation (but not). Secondly, when the line that contain the structure breaks, the item indicators also align, presuming the use of an enumerated list. How can I reasonably assume this is done? Does it have to be a forced method, as a table, or can it be a flexible one, like inline?
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I am trying to compile a document with equations but whenever I use \begin{eqnarray}..\end{eqnarray} or \begin{align}...\end{align} or anything like this I get the error msg !Missing $ inserted.&lt;inserted text&gt;$. However if I type those equations without using \begin{eqnarray}...\end{eqnarray} or similar things I do not get any error msg and my document runs perfectly.  Even this simple thing does't work....Please help...  \documentclass[a4paper,12pt]{article} \usepackage{amsmath} \usepackage{amssymb}  \begin{document}  \begin{align} $=$  \end{align} \end{document}
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How do I insert the line "|" after the equation in LaTeX (see image below)? I'm using LyX so if you can point me to the symbol of that line is also OK.    I don't know if this line has a proper name so the title of this question may be very vague. If you could provide me a name, I'll edit this question's title.
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Here is my code:   \begin{align*} (a-bu)e^{-\frac{1}{4}(v^2+u^2)(1+c)+\frac{1}{2}(1-c)u|v|}  &amp;=(a-bx-by)e^{-\frac{1}{4}((x-y)^2+(x+y)^2)(1+c)+\frac{1}{2}(1-c)(x+y)(y-x)}\\ &amp;=(a-bx-by)e^{-(x^2+cy^2)} \\ &amp;=f(x,y). \end{align*}   I have a long equation. My question is as follows: I want to isolate the expression   (a-bu)e^{-\frac{1}{4}(v^2+u^2)(1+c)+\frac{1}{2}(1-c)u|v|}   on the first line so that I don't have an equation on the first line and I want this expression left justified with the other lines (that have the equal sign). How can I do this?
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I'm using aligned inside align as follows   \documentclass{article} \usepackage{amsmath} \begin{document} \begin{align} x =&22+2 \nonumber\\   =& \begin{aligned}[t]     &5+3\\     &-3+4\\     &+15-0   \end{aligned} \end{align} \end{document}   I want to have just one equation number after the very last line.  However, I'm getting the number at the beginning of the first split line (after the second = ),    and I cannot figure out how to move this equation number to the bottom. Any help will be appreciated.
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After some brief searching I can't find the difference between align and align*. Google summarily ignoring the * is making it harder I think.  Can you tell me the difference between these two?  Moreover, can you tell me where you generally go for this type of information? As a relatively new user I'm still building up my resources.
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Let's say I have written an equation in my paper and numbered it:  y = a + bx    (1)   Then, later in the paper, I want to remind the reader by showing the same equation with the same equation number.  Sure, I can repeat the equation, but LaTeX gives it a new equationn number:  y = a + bx     (2)   How do I force LaTeX to use the original equation numbers?
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I am writing two equations in an align environment:  \begin{align} x^2+y^2=z^2, \\ x^2=7, \end{align}   I would like the first equation to be labelled with e.g. (1.1) and the second equation to be labelled (1.1'), rather than (1.2).  Is this possible to automate? Do I need to use a hack to manually place the equation number after my second equation? e.g.  \newcommand{\hack}{\hfill({\eqnum}')} % Sketch - I don't know what command to use. \begin{align} x^2+y^2=z^2, \\\nonumber x^2=7,\hack \end{align}   If so, what command can I use to get the equation number? i.e. what should my command \hack be?
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I understand that the expressions on both sides of an equal sign are the same entity, and I know that when you modify one side, the other must be changed because it is referring to the same thing. What I do not understand is why making a new equation (adding or taking away from an expression) allows one to know what an unknown represents. What about equations lets us do this?
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I have an align environment with 5 equations. I want 3 of them numbered, and the other 2 not numbered. I understand that there's other posts on the issue of selective numbering of those equations that are referred to in the body of the text, but that's different to what I'm trying to achieve.  I want the first three lines (equations) of the following to be numbered and the last two to be without numbering. Thanks.  \documentclass[a4paper,11pt]{article} \usepackage[fleqn]{amsmath} \begin{document}  \begin{align} &amp;R_{i,t} = \alpha_i  \\ &amp;R_{i,t} = \beta_i  \\ &amp;R_{i,t} = \gamma_i  \\ &amp;\mathbb{E}[\epsilon_{it}]=0;\textrm{   } \textrm{Var}[\epsilon_{it}]=\sigma^2_{\epsilon_{i}}\\ &amp;i \in \{1,2,...,N\};\textrm{   } t \in \{1,2,...,T\} \end{align}  \end{document}
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I'm currently typing a mathematical document which counts many sum symbols. I frequently use the align environment to render equations, although the default behaviour of this environment is to render the equations in displaystyle, which in my opinion wastes vertical space. I therefore have added \textstyle at the beginning of each line of math in this environment, but I'm looking for a more convenient solution.   So is there an environment that is similar to align with the exception it displays textstyle math by default ? Thank you.