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I am trying to typeset synthetic division. I am using the following code:

\[
\left.\begin{array}[t]{c}1\\ \,\end{array}\right|\!\begin{array}[t]{cccc}1& 2& -5& 2\\ & 1& 3& -2\\ \hline 1& 3& -2& 0\end{array}
\]

The output I get is the following:

enter image description here

Why does the vertical line go way beyond the top of the array?

I need a vertical line of the size of the first two lines of the array on the right. I am trying to achieve it using KaTeX so I can only use the commands KaTeX supports. Adding extra packages is not possible.

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1 Answer 1

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2

Why not simply use this code?

\[
\begin{array}[t]{c|}1\\ \,\end{array}\enspace \begin{array}[t]{rrrr}1& 2& -5& 2\\ & 1& 3& -2\\ \hline 1& 3& -2& 0\end{array}
\]

enter image description here

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5
  • Yes, indeed, I have not thought about it, but it works perfectly. Thank you! Nevertheless, I would still be curious why is my code giving longer delimiter. It seems, that the top alignment confuses \left \right.
    – Ferenc Beleznay
    Dec 12, 2019 at 22:42
  • Probably it is because the (unique) row – or the array – has some invisible spacing at the top.
    – Bernard
    Dec 12, 2019 at 22:46
  • I tried adding text around this line, it did not make a difference.I also changed it to inline math, it did not make a difference either. I do not think there is some invisible space in the array, I think it would also make the vertical line in your edit go up.I was thinking about it a bit more and I rather think that the \left ... \right height is calculated symmetric to the alignment position, which in this case produces a strange looking result.
    – Ferenc Beleznay
    Dec 13, 2019 at 6:53
  • I think you have the correct explanation.
    – Bernard
    Dec 13, 2019 at 8:20
  • @FerencBeleznay yes which is the issue the delarray package addresses, it shifts the delimiter alongside the array as you use [t] or [b]
    – David Carlisle
    Dec 13, 2019 at 9:13

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