[Tex/LaTex] alignment inside split and align

alignamsmathmath-modesplit

I would like to have (Kollo Skewness) to be aligned on the right with (Row Sums) and (Orthogonality) while keeping (4.16) in between the third and fourth line.

This is my code

\begin{align} 
    &\mathbf{L}_{mn}'\mathbf{L}_{mn}  = m \mathbf{I}_n & \text{(Orthogonality)}\\
    &\mathbf{1}_m^{'} \mathbf{L}_{mn}  = \mathbf{0}'_n & \text{(Row Sums)} \\
    \begin{split} \label{eq:kollo:b}
        &\mathbf{b} = m^{-1} \left[ s_1 \mathbf{c}_1 + \dots + s_m \mathbf{c}_m  \right]  \text{(Kollo skewness)}\\
        &\text{where} \quad s_k = \left(c_{1k} + \dots + c_{nk}  \right)^2 = \left( \mathbf{1}' \mathbf{c}_k \right)^2 
    \end{split}
\end{align}

This might have also been answered elsewhere. If so please point me there. I was unable to find it.

This is a minimum example

\documentclass[12pt,a4paper]{report}
\usepackage{amsmath,amsfonts,amsthm}
\setlength{\topmargin}{1.5cm}
\setlength{\headheight}{15pt}
\setlength{\headsep}{20pt}
\setlength{\topskip}{12pt}
\setlength{\evensidemargin}{0pt}
\setlength{\oddsidemargin}{0pt}
\setlength{\textheight}{240mm}
\setlength{\textwidth}{160mm}
\setlength{\voffset}{-2cm}
\setlength{\parindent}{0pt}
\setlength{\parskip}{6pt}


\begin{document}
\begin{align} 
    &\mathbf{L}_{mn}'\mathbf{L}_{mn}  = m \mathbf{I}_n & \text{(Orthogonality)}\\
    &\mathbf{1}_m^{'} \mathbf{L}_{mn}  = \mathbf{0}'_n & \text{(Row Sums)} \\
    \begin{split} \label{eq:kollo:b}
        &\mathbf{b} = m^{-1} \left[ s_1 \mathbf{c}_1 + \dots + s_m \mathbf{c}_m  \right]  \text{(Kollo skewness)}\\
        &\text{where} \quad s_k = \left(c_{1k} + \dots + c_{nk}  \right)^2 = \left( \mathbf{1}' \mathbf{c}_k \right)^2 
    \end{split}
\end{align}
\end{document}

Best Answer

Here are two different possible alignments, with aligned instead of split:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{fourier}
\usepackage{mathtools}
\usepackage{cleveref}

\begin{document}

\begin{align}
    &\mathbf{L}_{mn}'\mathbf{L}_{mn} = m \mathbf{I}_n & \text{(Orthogonality)}\\
    &\mathbf{1}_m^{'} \mathbf{L}_{mn} = \mathbf{0}'_n & \text{(Row Sums)} \\
     & \begin{aligned}[t] \label{eq:kollo:b}
        &\mathbf{b} = m^{-1} \left[ s_1 \mathbf{c}_1 + \dots + s_m \mathbf{c}_m \right]\\
        &\quad\text{where} \quad s_k = \left(c_{1k} + \dots + c_{nk} \right)^2 = \left( \mathbf{1}' \mathbf{c}_k \right)^2
    \end{aligned} & \text{(Kollo skewness)}
\end{align}

\Cref{eq:kollo:b}

\begin{align}
    &\mathbf{L}_{mn}'\mathbf{L}_{mn} = m \mathbf{I}_n & & \text{(Orthogonality)}\\
    &\mathbf{1}_m^{'} \mathbf{L}_{mn} = \mathbf{0}'_n & & \text{(Row Sums)} \\
     & \begin{aligned}[t] \label{eq:kollo:c}
        &\mathbf{b} = m^{-1} \left[ s_1 \mathbf{c}_1 + \dots + s_m \mathbf{c}_m \right]\\
        &\quad\text{where} \quad s_k = \left(c_{1k} + \dots + c_{nk} \right)^2 = \left( \mathbf{1}' \mathbf{c}_k \right)^2
    \end{aligned} & & \text{(Kollo skewness)}
\end{align}

\end{document}

Related Solutions

[Tex/LaTex] AMS Split inside AMS Align

I don't know what you are trying to achieve. Your error message can be bypassed if you either increase the number of reference points in the alignat

\begin{alignat*}{2}
= & \begin{split} x+ \\
y\end{split}
\end{alignat*}

or if you use aligned instead of split

\begin{alignat*}{1}
= & \begin{aligned} x+ \\
y\end{aligned}
\end{alignat*}

With split, it tries to anchor its & to line up with the ones outside (so multiple splits inside one equation will line up). So implicitly you need one extra reference point if you use split inside alignat, which is just a glorified array. (I'm doing a horrible job explaining this, am I not?) aligned doesn't try to do that (two aligned blocks inside one equation won't line up), and so you can get by with just one reference point.

In anycase, either of this sets the broken expression x+y as one unit to the right, vertically centered, against the = sign, which I suspect may not be what you want. If you want the = to line up with the x+ and with the y in a line below, you should take Lev's suggestion.

[Tex/LaTex] Combine split and align environment

This is the aligned environment:

\begin{equation}
\begin{aligned}
 a&=1+2+3 & b&=4+5+6\\
 c&=2+4+6 & d&=3+5+7
\end{aligned}
\end{equation}

If you want to have control on the gap between groups of alignments, you can use the alignedat{n} environment, where n is the number of groups, requiring 2n-1 ampersands.

\begin{equation}
\begin{alignedat}{2}
 a&=1+2+3 &\hspace{1in}b&=4+5+6\\
 c&=2+4+6 & d&=3+5+7
\end{alignedat}
\end{equation}

As pointed by egreg, the tbtags option doesn't work in that case, so that one has either to use the [t] or [b] option of the aligned/alignedat environments, or to use an align/aligned environment and the \notag command at the relevant places:

\begin{equation}
\begin{alignedat}[b]{2}
 a&=1+2+3 &\hspace{1in} b&=4+5+6\\
 c&=2+4+6 & d&=3+5+7
\end{alignedat}
\end{equation}

\begin{alignat}{2}
 a&=1+2+3 &\hspace{1in} b&=4+5+6\notag\\
 c&=2+4+6 & d&=3+5+7
\end{alignat}

Best Answer

Related Solutions

[Tex/LaTex] AMS Split inside AMS Align

[Tex/LaTex] Combine split and align environment

Related Question