I sent the following reply but the list bounced it (as I wasn't
subscribed as davidc@nag:-) so I'll resend now. In the meantime
I see Donald Arseneau also replied. Fortunately I think his reply agrees
with this!


Date: 14 Apr 1998 17:58:54 +0100
From: David Carlisle <[log in to unmask]>
To: [log in to unmask]
In-reply-to: <[log in to unmask]> (message
        from Volker Schubert on Tue, 14 Apr 1998 16:07:32 +0200)
Subject: Re: Arrays
Reply-To: [log in to unmask]

> The problem here is that there is no minimal vertical space between
> the lines.

There are some packages which extend the latex system to provide for a
mininmum amount of white space above the table entries. Unfortunately
doing this makes the packages usually incompatible to a greater or
lesser extent to each other and to other latex table packages.

But tabls.sty mdwtab.sty and colortab.sty all offer something along
these lines. Not specifically for math material, your example, but
more generally forcing the table system to insert a minimum amount of
space between each line. It is hard to come up with a really good
solution to this while preserving the existing latex syntax for
rules and inter-column material such as @{...}. It is not essential
that all latex array packages preserve the existing syntax, but coming
up with an alternative has not proved too easy in the past!

> It would be nice if there was a generalized equation environment,
> where one can give arbitrary preambles for the horizontal alignment.

what sort of things do you want to specify. Not the syntax, which is
not so important, but what `arbitrary' information do you have in mind?

> if there was an argument-switch in the
> alignment-environment where one could turn on ``\displaymode in
> every column''.

I'm  tempted to say do
\sum_1^2x & \frac{a}{b}
but perhaps that makes more display mode than you intended.