3

Here is my code: ‎

\begin{eqnarray}\label{eq:diff_inv}‎ 
‎&\mathcal{D}_1 I_{10}=I_{20}-\frac{3}{2}I_{01},\qquad &\mathcal{D}_2 I_{10}=I_{11}-\frac{3}{2}I_{10}I_{01},\\‎ 
‎&\mathcal{D}_1 I_{01}=I_{11}-\frac{5}{2}I_{10}I_{01},\qquad &\mathcal{D}_2 I_{01}=I_{02}-\frac{5}{2}I_{01}^2‎, ‎\nonumber\\‎ 
‎&\mathcal{D}_1 I_{10}=I_{20},\qquad &\mathcal{D}_2 I_{10}=I_{11},\label{eq:diff_inv_55}\\‎ 
‎&\mathcal{D}_1 I_{01}=I_{11}+\alpha\,I_{01}I_{01},\qquad &\mathcal{D}_2 I_{01}=I_{02}+I_{01}^2‎, ‎\nonumber‎
‎\end{eqnarray}‎

and here is the result:

enter image description here

But I want this alignment:

enter image description here

Ingmar
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Mustafa Bazghandi
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    as zarko says but also avoid control characters in your input, ! LaTeX Error: Unicode character ‎ (U+200E) not set up for use with LaTeX. – David Carlisle Aug 23 '22 at 18:28

2 Answers2

8

Either align or alignat{n} are meant for this kind of equations

enter image description here

The pattern is following: groups consist of right & left aligned elements and each group is separated by another ampersand &. For instance, there are two groups in your example

  right & left   &   right & left \\

alignat{n} is similar but does not add extra space between columns. n is mandatory and denotes a number of groups, in your case 2

\documentclass{article}
\usepackage{mathtools}

\begin{document}
\begin{align}
  \mathcal{D}1 I{10} &= I_{20} - \frac{3}{2}I_{01},
        & \mathcal{D}2 I{10} &= I_{11} - \frac{3}{2}I_{10 }I_{01}, \
  \mathcal{D}1 I{01} &= I_{11} - \frac{5}{2}I_{10}I_{01},
        & \mathcal{D}2 I{01} &= I_{02} - \frac{5}{2}I_{01}^2,      \nonumber \
  \mathcal{D}1 I{10} &= I_{20},
        & \mathcal{D}2 I{10} &= I_{11},                            \label{eq:diff_inv_55} \
  \mathcal{D}1 I{01} &= I_{11} + \alpha,I_{01}I_{01},
        & \mathcal{D}2 I{01} &= I_{02} + I_{01}^2,                 \nonumber
\end{align}


\end{document}
Celdor
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5

Edit: In your code is somewhere hidden character which not allow to compile it with pdfLaTeX. Now I rewrite equation (from scratch) and MWE works as expected :-)

Like this?

enter image description here

Use of eqnaray is deprecated. Better is use align of amsmath package:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
    \begin{align}
\mathcal{D}1 I{10}
    & = BI_{20} - \frac{3}{2} I_{01}    &   \mathcal{D}1 I{10}
                                                & = I_{11} - \frac{3}{2} I_{10} I_{10}          \
\mathcal{D}1 I{01}
    & = I_{11}-\frac{5}{2}I_{10}I_{01}  &   \mathcal{D}2 I{01}
                                                & = I_{02} - \frac{3}{2} I_{01}^2       \notag  \
\mathcal{D}1 I{10}
    & = I_{11}-\frac{5}{2}I_{10}I_{01}  &   \mathcal{D}2 I{10}
                                                & = I_{11}              \label{eq:diff_inv_55}  \
\mathcal{D}1 I{01}
    & = I_{11}-\alpha I_{10}I_{01}      &   \mathcal{D}2 I{01}
                                                & = I_{02} + I_{01}^2                   \notag

    \end{align}
\end{document}
Zarko
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