20

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}
3
  • 1
    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, 2015 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? Mar 13, 2015 at 18:34
  • And how do you make reference for each individual subproblem in a text?
    – Christina
    Aug 5, 2017 at 8:33

3 Answers 3

30

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

16

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

2
  • @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. May 18, 2017 at 15:22
  • 2
    @rudreshdwivedi --- After the double backslash, use \intertext{and}. May 18, 2017 at 15:36
7

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

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