[Tex/LaTex] Writing a text side by side an equation in \align environment

equations

I have a very long equation in \align* environment so that I split it into two lines as shown in the screenshot blew

I want to write some text side to side the above part of the equation using &&\text{} ,but Latex throw it away in the margins and I do not know why this happens. Here is my code regarding this part :

\begin{align*}
X_{p}\psi &=  
X_p\bigl( \psi(p) \bigr) 
 + \sum_i \left(\left.\frac{\partial \psi}{\partial x^{i}}\right|_{p} \right) X_{p}\left(x^{i}-a^{i}\right)           &&\text{(plaplapla)} \\
&\phantom{{}= }+ \sum_i \sum_j X_{p}\left( \left(\zeta_{ij}\circ\phi \right)\left(x^{i}-a^{i}\right)\left(x^{j}-a^{j} \right) \right) .

The first & is using for aligning equations later, any my preamble just has the necessary packages for mathematics.

I appreciate any help. Thanks in advance.

Best Answer

Assuming the explanatory text string isn't all that long, it should be enough to separate it from the other material in the first row with a \quad or \qquad directive.

I would also like to recommend strongly that you get rid of the habit of using \left and \right with all math-mode parentheses. See, e.g., Is it ever bad to use \left and \right? for more information on this subject.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\hrule % Just to illustrate the width of the text block -- feel free to omit!
\begin{align*}
X_{p}\psi &= X_p\bigl( \psi(p) \bigr) 
  +\sum_i \biggl(\frac{\partial\psi}{\partial x^{i}}\biggr|_{p}\,\biggr) X_{p}(x^{i}-a^{i}) 
  \qquad\text{some explanatory thoughts}\\
&\quad+ \sum_i \sum_j X_{p}\bigl( (\zeta_{ij}\circ\phi)(x^{i}-a^{i})(x^{j}-a^{j}) \bigr) .
\end{align*}
\end{document}

Related Solutions

[Tex/LaTex] Left-align {align} environment

use it this way:

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\begin{align}
u(x+\Delta x, t) &= u(x,t) +\frac{\partial u(x,t)}{\partial x}\Delta x +\frac{\partial u(x,t)}{\partial t}(t-t) + \frac12\frac{\partial^2 u(x,t)}{\partial x^2}(\Delta x)^2 \\
                 & \qquad + \frac{\partial^2u(x,t)}{\partial x\partial y}(t-t)(\Delta x)^2 + \frac12\frac{\partial u(x,t)}{\partial^2t}(t-t)^2 \\
                 & \qquad +(...)\Delta x^3 +(...)\Delta x^4 
\intertext{Seeing powers of t dropping in expansion around $x\pm\Delta x$}
u(x-\Delta x, t) &= u(x,t) -\frac{\partial u(x,t)}{\partial x}\Delta x +  \frac12\frac{\partial^2 u(x,t)}{\partial x^2}(\Delta x)^2 -(...)\Delta x^3 +(...)\Delta x^4\\
 & \left[\frac12\frac{\partial^2 u(x,t)}{\partial x^2}(\Delta x)^2+ \frac12\frac{\partial^2 u(x,t)}{\partial x^2}(\Delta x)^2\right] \\
 & = u(x-\Delta x, t) + u(x+\Delta x, t) - u(x,t) - u(x,t) + O(\Delta x^4)
\intertext{Odd powers of $\Delta x$ cancelling eachother}
  \frac{\partial^2 u(x,t)}{\partial x^2} &= \frac{u(x-\Delta x, t) + u(x+\Delta x, t) - 2u(x,t)}{\Delta x^2} + O(\Delta x^2)
\end{align}

\end{document}

enter image description here

[Tex/LaTex] Large formula in align

To obtain a centred "first part" and only have two parts, I assume you just want the whole things centred. For this you just have to gather* the contents:

enter image description here

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\begin{gather*}
  \log \mathcal{L}(\alpha,\beta,\mu,\delta|  l_1,...,l_n) = \\
  \sum_{i=1}^n  \left( \log \left(\frac{\sqrt{\alpha^2-\beta^2}}{2\alpha \delta K_1 (\delta\sqrt{\alpha^2-\beta^2})} \exp\left(-\alpha\sqrt{\delta^2+(l-\mu)^2}+\beta(l-\mu)\right)\right) \right)
\end{gather*}
\end{document}

Note the use of \log as an operator for logarithm.

Best Answer

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[Tex/LaTex] Left-align {align} environment

[Tex/LaTex] Large formula in align

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