[Tex/LaTex] Right align text in align environment, while keeping maths centered

alignflalign

I use text at some lines of an align environment to justify how we go from one line to another.
I would like to keep the maths centered, and text to be aligned to the right, but I did not succeed:

  \begin{align}
    a &= bbbbbb &\nonumber \\
    cccc  & =  dd & \text{(using Eq. 1)} & \nonumber \\
    e &= f & \text{(using Thm. 2)} 
  \end{align}

gives

which is OK for the maths, but not for the text as it is not completely at the end of the lign.

Using the flalign environement instead aligns the math equations to the left, while I'd like to keep them centered.

What is the cleanest way to achieve this ?

Best Answer

I propose one of these two dolutions, both based on the flalign environment:

\documentclass{article}
\usepackage{mathtools}
\usepackage{eqparbox}
\usepackage[showframe]{geometry}

\begin{document}

  \begin{flalign}
  & & a &= bbbbbb &\nonumber \\
 & & cccc & = dd & \text{(using Eq. 1)} & \nonumber \\
 & & e &= f & \text{(using Thm. 2)}
  \end{flalign}

  \begin{flalign}
  & & a &= bbbbbb \nonumber \\
 & & cccc & = dd & \eqparbox{C}{(using Eq. 1)} & \nonumber \\
 & & e &= f & \eqparbox{C}{(using Thm. 2)}
 \end{flalign}

\end{document}

Related Solutions

[Tex/LaTex] Aligning multiline equation to the left with only one equation number

You can put a whole split inside the first field of flalign, or better used aligned here:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{flalign}
  \begin{aligned}
F\{j(t)\}=&-\tfrac{j_{\max}}{2\pi jf}e^{-2\pi jf\frac{a_{\max}}{j_{\max}}}+\tfrac{j_{\max}}{2\pi jf}+\tfrac{j_{\max}}{2\pi jf}e^{-2\pi jf(\frac{v_{\max}}{a_{\max}}+\frac{a_{\max}}{j_{\max}})} \\
    &-\tfrac{j_{\max}}{2\pi jf}e^{-2\pi jf\frac{v_{\max}}{a_{\max}}}
  \end{aligned}&&&
\end{flalign}

\end{document}

The aligned building block can be used anywhere inside other math constructions. split is more restricted.

Vertically centred equation number in multiline equation while maintaining alignment with other equations in flalign environment

I suggest you place rows 2 and 3 inside nested aligned environments.

The following screenshot shows the outputs of both your original code and the suggested replacement code.

Speaking for myself, I can't help but wonder what you could possibly be trying to achieve by centering the second equation number across rows 2 and 3 of the 3-row construct. That said, I also can't fathom why you're using an flalign environment instead of an align environment.

\documentclass{article}
\usepackage{mathtools,calc,xcolor}
\newcommand\mybox[1]{%
   \parbox{\widthof{$AAA$}}{\raggedleft$\displaystyle #1 $}}
\begin{document}

\noindent
\textcolor{red}{before}
\begin{flalign}
            AAA &= 2 X Y - D Z & \\
            B &= 2 X Y \left( h_1 v_1 + v_2 \right) & \nonumber  \\
                & \qquad - X^3 \left( 2 h_2 v_2 + K_2 \right) & 
\end{flalign}

\bigskip\noindent
\textcolor{red}{after}
\begin{flalign}
       &AAA = 2 X Y - D Z & \\
       &\begin{aligned}
          \begin{aligned}
            &\mybox{B} = 2 X Y ( h_1 v_1 + v_2 )  \\
            & \qquad\qquad - X^3 ( 2 h_2 v_2 + K_2 ) 
          \end{aligned}
        \end{aligned}
\end{flalign}
    
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Aligning multiline equation to the left with only one equation number

Vertically centred equation number in multiline equation while maintaining alignment with other equations in flalign environment

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