Augmented matrix is not produced correctly

[Paul Smith]

On Wed, May 6, 2020 at 5:13 PM Paul A. Rubin <parubin73 at gmail.com> wrote:
>
> >> I suspect that I have found a bug: When I do what I do at the attached
> >> screenshot, I do not get what one would have expected (the vertical
> >> line drawn between the first and the second column).
> >>
> >> This discussion may be relevant:
> >>
> >> https://tex.stackexchange.com/questions/299221/adding-vertical-line-equal-sign-to-augmented-bmatrix-without-using-array
> >>
> >> What version of LyX are you using? I get the vertical line using LyX 2.3.4.2 on Linux Mint.
> > Thanks, Paul. I am using
> >
> > LyX Version 2.3.4.2
> >
> > on Fedora Linux 31.
> >
> > Have you selected the matrix decoration as [x], Paul?
> >
> > As soon as one does that, LyX uses bmatrix environment, with which it
> > is impossible to get an augmented matrix.
> >
> Sorry, missed that part. You're right, that does nuke the vertical line.
> A workaround is to use the [] math toolbar button to create the brackets
> and insert the matrix inside. It's not perfect -- there seems to be more
> white space between brackets and matrix -- but it's in the ballpark.

No, Paul. There is a better approach: The one presented at the
web-address I mention on my initial message: In the horizontal
alignment, insert:

@{}c|c@{}

and select no matrix decoration. Then enter the brackets as you
suggested. You will see that the extra white space between brackets
and matrix will be gone.

I would suggest that LyX implements this approach: Augmented matrices
are shown very nicely and neatly.

Paul