Math & Science ⇒ Vertical alignment in array environment

[chen]

Hi, I've got a nested array that outputs:

2me74o2.jpg (22.46 KiB) Viewed 16275 times

with code:

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$$\begin{array}[t]{ll}
\min &x_1 - x_2 \\
\textup{s.t.} &\begin{array}{lclll}
         5y_1 & \leq & x_1 & \leq & 12y_1+2\\
         y_2  & \leq & x_2 & \leq & 9(1-y_2) + 1\\
         3y_3  & \leq & x_2 & \leq & 7(1-y_3) + 3\\
         5y_4  & \leq & x_2 & \leq & 5(1-y_4) + 5\\
         10y_5 & \leq & x_2 & \leq & 10\\
        \end{array}\\
        &x_1, x_2 \geq 0\\
        &x_2 \in \ZZ\\
\end{array}$$

but I would like it to look like:

25zqtrd.jpg (22.38 KiB) Viewed 16275 times

I've been tearing my hair out all day - I've been trying to look up stuff like vertical alignment with the array environment but just got absolutely nowhere.

Thanks very much.


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[Stefan Kottwitz]

Hi Chen,

you already used the optional positional argument t. Do it again for the array inside:

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\textup{s.t.} &\begin{array}[t]{lclll}

This way s.t. would align with the top of the array like desired.

Btw. I would prefer an aligned or align environment instead of array, further \[ ... \] instead of $$...$$.

Stefan

[chen]

Thanks - but also, how can I remove the left padding the nested array so that the 5y_1 on the second line and so on lines up with x_1 on the first line? And how can I reduce the gap between the <=s? Thanks.

[Stefan Kottwitz]

how can I remove the left padding the nested array so that the 5y_1 on the second line and so on lines up with x_1 on the first line?

Insert @{}:

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\textup{s.t.} &\begin{array}[t]{@{}lclll}

And how can I reduce the gap between the <=s? Thanks.

User further @{}:

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\textup{s.t.} &\begin{array}[t]{@{}l@{}c@{}l@{}l@{}l}

No space is a bit extreme ... so you might use something like @{\,} or @{\hspace{...}} instead.

Stefan