subequations align

Question

Can anyone help me fix this problem? enter image description here Actually, there is no need to have 1(b), 1(d), 1(f) and 1(h) since they are deriving from the last line. Can I have just four subequations?

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{subequations}
\begin{alignat}{4}
E_{11}&=Q_{11}^2\ln\sqrt{B'_{11}} +Q_{12}^2\ln\sqrt{B'_{22}}+Q_{13}^2\ln\sqrt{B'_{33}}\\
&=Q_{11}^2\ln\sqrt{B'_{11}}+Q_{21}^2\ln\sqrt{B'_{33}}\\
E_{12}&=Q_{11}Q_{21}\ln\sqrt{B'_{11}}     +Q_{12}Q_{22}\ln\sqrt{B'_{22}}+Q_{13}Q_{23}\ln\sqrt{B'_{33}} \\
&=Q_{11}Q_{21}\ln\sqrt{B'_{11}}-Q_{11}Q_{21}\ln\sqrt{B'_{33}}\\
E_{22}&=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{22}^2\ln\sqrt{B'_{22}}+Q_{23}^2\ln\sqrt{B'_{33}}\\
&=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{11}^2\ln\sqrt{B'_{33}}\\
E_{33}&=Q_{31}^2\ln\sqrt{B'_{11}} +Q_{32}^2\ln\sqrt{B'_{22}}+Q_{33}^2\ln\sqrt{B'_{33}}\\
&=Q_{32}^2\ln\sqrt{B'_{22}}
\end{alignat}
\label{straincomponent}
\end{subequations}

\end{document}

I prefer to put \label{straincomponent} next to \begin{subequations}, where it's more easily seen; it changes nothing in the output, of course. — egreg, Mar 13 '15 at 17:24
Please start accepting answers to mark your questions as solved. As I told you in other questions of yours, please see How do you accept an answer? — karlkoeller, Mar 13 '15 at 18:34
And how do you make reference for each individual subproblem in a text? — Christina, Aug 05 '17 at 08:33

score 30 · Answer 1 · answered Mar 13 '15 at 17:43

another variation, with the equation number for each pair positioned vertically between the two lines:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{subequations}
\begin{align}
\begin{split}
E_{11}&=Q_{11}^2\ln\sqrt{B'_{11}} +Q_{12}^2\ln\sqrt{B'_{22}}+Q_{13}^2\ln\sqrt{B'_{33}}\\
&=Q_{11}^2\ln\sqrt{B'_{11}}+Q_{21}^2\ln\sqrt{B'_{33}}
\end{split}\\
\begin{split}
E_{12}&=Q_{11}Q_{21}\ln\sqrt{B'_{11}}     +Q_{12}Q_{22}\ln\sqrt{B'_{22}}+Q_{13}Q_{23}\ln\sqrt{B'_{33}} \\
&=Q_{11}Q_{21}\ln\sqrt{B'_{11}}-Q_{11}Q_{21}\ln\sqrt{B'_{33}}
\end{split}\\
\begin{split}
E_{22}&=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{22}^2\ln\sqrt{B'_{22}}+Q_{23}^2\ln\sqrt{B'_{33}}\\
&=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{11}^2\ln\sqrt{B'_{33}}
\end{split}\\
\begin{split}
E_{33}&=Q_{31}^2\ln\sqrt{B'_{11}} +Q_{32}^2\ln\sqrt{B'_{22}}+Q_{33}^2\ln\sqrt{B'_{33}}\\
&=Q_{32}^2\ln\sqrt{B'_{22}}
\end{split}
\end{align}
\label{straincomponent}
\end{subequations}
\end{document}

output of example code

score 16 · Answer 2 · answered Mar 13 '15 at 17:15

Use \nonumber in the lines where you don't want a label.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{subequations}
\begin{alignat}{4}
E_{11}&=Q_{11}^2\ln\sqrt{B'_{11}} +Q_{12}^2\ln\sqrt{B'_{22}}+Q_{13}^2\ln\sqrt{B'_{33}}\\
      &=Q_{11}^2\ln\sqrt{B'_{11}}+Q_{21}^2\ln\sqrt{B'_{33}}\nonumber\\            
E_{12}&=Q_{11}Q_{21}\ln\sqrt{B'_{11}}     +Q_{12}Q_{22}\ln\sqrt{B'_{22}}+Q_{13}Q_{23}\ln\sqrt{B'_{33}} \\ 
      &=Q_{11}Q_{21}\ln\sqrt{B'_{11}}-Q_{11}Q_{21}\ln\sqrt{B'_{33}}\nonumber\\ 
E_{22}&=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{22}^2\ln\sqrt{B'_{22}}+Q_{23}^2\ln\sqrt{B'_{33}}\\ 
      &=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{11}^2\ln\sqrt{B'_{33}}\nonumber\\
E_{33}&=Q_{31}^2\ln\sqrt{B'_{11}} +Q_{32}^2\ln\sqrt{B'_{22}}+Q_{33}^2\ln\sqrt{B'_{33}}\\ 
      &=Q_{32}^2\ln\sqrt{B'_{22}}\nonumber    
\end{alignat}
\label{straincomponent}
\end{subequations}

\end{document}

enter image description here

@Windy if i want to put an [and] between equation 1(a) and 1(b), what i should do. I did \text{and} but i got an error. — rudresh dwivedi, May 18 '17 at 15:22
@rudreshdwivedi --- After the double backslash, use \intertext{and}. — Ian Thompson, May 18 '17 at 15:36

score 7 · Answer 3 · answered Mar 13 '15 at 17:38

A variant, with a single align and 4 aligned environments. I added some vertical spacing between the groups of equations:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{subequations}
  \begin{align}%{4}
    E_{11} & \!\begin{aligned}[t] & = Q_{11}^2\ln\sqrt{B'_{11}} +Q_{12}^2\ln\sqrt{B'_{22}}+Q_{13}^2\ln\sqrt{B'_{33}} \\
    &=Q_{11}^2\ln\sqrt{B'_{11}}+Q_{21}^2\ln\sqrt{B'_{33}}
    \end{aligned}\\[0.75ex]
    E_{12} & \!\begin{aligned}[t] & =Q_{11}Q_{21}\ln\sqrt{B'_{11}} +Q_{12}Q_{22}\ln\sqrt{B'_{22}}+Q_{13}Q_{23}\ln\sqrt{B'_{33}} \\
    & =Q_{11}Q_{21}\ln\sqrt{B'_{11}}-Q_{11}Q_{21}\ln\sqrt{B'_{33}}
    \end{aligned}\\[0.75ex]
    E_{22} & \!\begin{aligned}[t] & =Q_{21}^2\ln\sqrt{B'_{11}} +Q_{22}^2\ln\sqrt{B'_{22}}+Q_{23}^2\ln\sqrt{B'_{33}} \\
    &=Q_{21}^2\ln\sqrt{B'_{11}} +Q_{11}^2\ln\sqrt{B'_{33}}
    \end{aligned}\\[0.85ex]
    E_{33} & \!\begin{aligned}[t] & =Q_{31}^2\ln\sqrt{B'_{11}} +Q_{32}^2\ln\sqrt{B'_{22}}+Q_{33}^2\ln\sqrt{B'_{33}} \\
    &=Q_{32}^2\ln\sqrt{B'_{22}}
    \end{aligned}
  \end{align}
  \label{straincomponent}
\end{subequations}

\end{document}

enter image description here

subequations align

3 Answers3

Linked