# Could I change the default column sep of aligned from \quad to \qquad globally?

I need your help: to change the default column sep of aligned from \quad to \qquad globally, thanks.

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An alternate route might be to use the alignedat environment, which allows you to choose the spacing between aligned elements. That is, the default spacing is zero, so the final spacing equals whatever space you choose to insert. – Phil Hirschhorn Mar 14 '11 at 5:03
give an example of what you really mean. aligned didn't use a \quad – Herbert Mar 14 '11 at 7:28
@ Herbert: My mistake. I had thought the space as a quad. So, I want a way to change the sep globally whatever it is a quad or not. @ Phil Hirschhorn: I've finish the draft, hard work to replace all aligned to alignedat, even alignedat is easy to customize. – user4169 Mar 14 '11 at 8:43

You could modify the value of \minalignsep:

\renewcommand*{\minalignsep}{2em}

It is 10pt by default. If you write this into your preamble, after loading amsmath, the change is globally, as desired. However, it's also valid for other align environments. That may be desired as well, to preserve consistent math environments.

By this redefinition you can keep the modification of \minalignsep local to aligned:

\makeatletter
\newenvironment{aligned}{%
\renewcommand*{\minalignsep}{2em}
\let\@testopt\alignsafe@testopt
\aligned@a
}{%
\crcr\egroup
\restorecolumn@
\egroup
}
\makeatother
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@ Stefan Kottwitz: Many thanks. Would you tell me which does "other align environments" mean? Include the "align" and "alignat" and "flalign" and the forth? Unless the align environment col sep will not increases, or it is not I want. – user4169 Mar 14 '11 at 9:00
@never shown: align and align* also use the same space between columns like aligned, which is meaningful. Do you also use several columns with align and wish to keep the space narrow, in contrast to aligned? If yes, aligned itself could be redefined or an internal macro could be changed, the first would be the better choice. – Stefan Kottwitz Mar 14 '11 at 9:11
You said right. I wrote some multiple lines structure with "align" but not "aligned" because "align" could be broken by page. If their col sep increases, I have to took much time to check the horizontal overflow boxs. But how to redifine the "aligned"? – user4169 Mar 14 '11 at 9:39
@never shown: I added an example redefinition of aligned. – Stefan Kottwitz Mar 14 '11 at 9:57
That's so good! Ever so much greatful! – user4169 Mar 14 '11 at 9:59