alignequations
I am writing long equations and each equation has to jump to a new page. I'm using
\begin{equation}
\begin{split}
............
\end{split}
\end{equation}
I've looked , but the only way I found , is using \begin{align*} and tagged it with
\tag{\stepcounter{equation}\theequation} but when I try to label it , I get an error:
Missing \endcsname inserted.\end{align*}
Without label works just fine.
Two solutions with alignat; one of them has two alignment points, the other, three, so that the numeric values are aligned on the integer part of the mantissa:
\documentclass[11pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\begin{document}
\begin{alignat}{3}
A_{0} & = -\frac{3σ_{1}' h H L²}{E (H+h)³} &&= - & & 1.62 × 10⁻⁶\,\mathrm{m} \\
B_{0} & = - \frac{3 h H (α_{2}-α_{1}) L²}{(H+h)³} &&= & & 2.95 × 10⁻⁸\,\mathrm{m\,K⁻¹} \\
C_{0} & = \frac{4 L³}{E W (H+h)³} &&= & & 1.08\,\mathrm{m\,N⁻¹}
\end{alignat}
\begin{alignat}{2}
A_{0} & = -\frac{3σ_{1}' h H L²}{E (H+h)³} &&= - 1.62 × 10⁻⁶\,\mathrm{m} \\
B_{0} & = - \frac{3 h H (α_{2}-α_{1}) L²}{(H+h)³} &&= 2.95 × 10⁻⁸\,\mathrm{m\,K⁻¹} \\
C_{0} & = \frac{4 L³}{E W (H+h)³} &&= 1.08\,\mathrm{m\,N⁻¹}
\end{alignat}
\end{document}
If you really want to scale the equations, do it properly:
\documentclass{article}
\usepackage{amsmath,graphicx}
\begin{document}
\begin{equation}
\resizebox{.8\textwidth}{!}{%
$\begin{aligned}
C_{M,i}(x) ={}
& -\frac{
e^{\mathrm{Ha}_{i} - x \frac{k}{D_{\mathrm{NO},t}}}
\bigl(
(-1 + e^{\mathrm{H\tilde{a}}_{i}})(-1+\mathrm{Mu}_{i} +
e^{\mathrm{H\tilde{a}}_{i}}(1+\mathrm{Mu}_{i}))Pr +
2e^{\mathrm{H\tilde{a}}_{i}} k\lambda_{\mathrm{air},i} C_{i}(t,z)
\bigr)
}{
2k(-1 + \mathrm{Mu}_{i} + e^{2(\mathrm{Ha}_{i}+\mathrm{H\tilde{a}}_{i})}(1+\mathrm{Mu}_{i}))
}
\\
& +\frac{
e^{\mathrm{Ha}_{i} + x \frac{k}{D_{\mathrm{NO},t}}}
\bigl(
(-1+e^{\mathrm{H\tilde{a}}_{i}})(-1+\mathrm{Mu}_{i} +
e^{\mathrm{H\tilde{a}}_{i}}(1+\mathrm{Mu}_{i}))Pr +
2e^{\mathrm{H\tilde{a}}_{i}} k\lambda_{\mathrm{air},i} C_{i}(t,z))
}{
2k(-1+\mathrm{Mu}_{i} + e^{2(\mathrm{Ha}_{i} + \mathrm{H\tilde{a}}_{i})}(1+\mathrm{Mu}_{i}))
}
\end{aligned}$%
}
\end{equation}
\end{document}
I removed all \left and \right; also all \, commands (they were wrong). I only used \bigl( and \bigr) in the outermost parentheses of the big expressions.
Don't use \text, but \mathrm in this context.
Best Answer
The
splitenvironment is meant to be used inside another environment, say, anequationenvironment. Thesplitenvironment does not provide its own numbering and labeling support; instead, it is assumed that the "outer" environment (in your case:equation) handles those chores. You appear to have "discovered" a way to get around this constraint through the use of nested\tagand\stepcounter{equation}instructions, but you've also discovered that the cross-referencing mechanism using\labeldirectives doesn't work.The
align*environment, by the way, is designed not to produce equation numbers, and that's why you have to resort to the same work-around as forsplitenvironments.Rather than devise an additional, and likely kludgy, fix to solve the cross-referencing problem (which might involve using
\refstepcounterinstead of\stepcounter, but you didn't learn this from me...), you should consider dropping the use ofalign*or nestedequation/splitenvironments and, instead, consider usingalignenvironments. Within analignenvironment, use\notag(or\nonumber)in those rows that should no get an equation number, and use\labelinstructions for the numbered lines you wish to be able to cross-reference using\refand friends.