[Tex/LaTex] Paragraph mode inside a math equation or reuse array-columns

horizontal alignmentmath-mode

My problem is that I want to reuse the spacing in a certain math equation like:

\begin{equation}
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
... & := &  ... \\[4mm]
    & =: &  ...
\end{array}
\end{equation}

This equation is followed by some text and then I want to repeat the above equation with the same spacings between array-columns. Is it possible? Out of the box I will get another spacing made by tex on the basis of the math symbols.

Perhaps it is possible to stick to one equation environment and insert the text in the equation. However \mbox{...} or \text{...} is not good enough because the text must show up in paragraph mode, left aligned w.r.t. the page.

W.r.t. the answer of Harish Kumar a MWE of my problem:

\documentclass{article}

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{mathtools}
\usepackage{relsize}
\usepackage{stmaryrd}
\usepackage{bm}

\begin{document}

\noindent 
Example 1 (not ok):
\begin{align}
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
a \cdot b & := &  a \cdot \mathlarger{\llbracket\,} 0, \, b \mathlarger{\,\rrbracket} \\[4mm]
    & =: &  ...
\end{array}
\intertext{In the group this means that ... }
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
a & = &  b.
\end{array}
\end{align}
Example 2 (ok):
\begin{align}
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
a \cdot b & := &  a \cdot b \\[4mm]
    & =: &  ...
\end{array}
\intertext{In the group this means that ... }
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
a & = &  b.
\end{array}
\end{align}

\end{document}

Best Answer

You can use align and (short)intertext:

\documentclass{article}
\usepackage{mathtools,lipsum}
\begin{document}
  \begin{align}
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
... & := &  ... \\[4mm]
    & =: &  ... 
\end{array}
\intertext{\lipsum*[1]}      %% or \shortintertext{\lipsum*[1]} from mathtools
\begin{array}{l@{\hspace{3mm}}c@{\hspace{3mm}}l}
... & := &  ... \\[4mm]
    & =: &  ... 
\end{array}
\end{align}
\end{document}

enter image description here

Dealing the edited question:

You can get rid of array too:

\documentclass{article}
\usepackage{showframe}   %% just for demo
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{mathtools}
\usepackage{relsize}
\usepackage{stmaryrd}
\usepackage{bm}

\newcommand{\h}[1]{\widehat{\bm{#1}}}
\newcommand{\he}{\ensuremath{\tfrac{1}{2}}}
\newcommand{\quat}[2]{\mathlarger{\llbracket\,} \cos{(\he#2)}, \, \sin{(\he#2)} \,\h{#1} \mathlarger{\,\rrbracket}}
\newcommand{\quatv}[1]{\mathlarger{\llbracket\,} 0, \,\h{#1} \mathlarger{\,\rrbracket}}

\begin{document}

\begin{align}
 \quatv{b} \cdot \quatv{a} & := \mathlarger{\llbracket} -\h{b}\cdot\h{a}, \, \h{b}\times\h{a} \mathlarger{\,\rrbracket} \quad \equiv \quad \mathlarger{\llbracket\,} \h{a}\cdot\h{b}, \, \h{a}\times\h{b} \mathlarger{\,\rrbracket} = \\[4mm]
 & =:  \quat{n}{\gamma}.\\
\intertext{In the group this means that ... }
 L_b \circ L_a & =:   R(\gamma \h{n}).
\end{align}

\end{document}

enter image description here

If this goes for long, you may add \allowdisplaybreaks in your preamble.

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