# Re: siunitx S columns

On Jan 20, 9:26 am, GL <gouail...@xxxxxxxxx> wrote:
A fixed width can be done in one pass. Just \hbox to <something>
as in the \halign example I gave in my previous post.

As I say, I may want to have a bit more subtly here as there are some
other issues that people also want me to address and which are not so
easy to do without first constructing each 'part' on it's own, and
then constructing the final result. However, in general you are right,
and I can certainly look to add this.

A minimum width implies the whole table to be evaluated before
making the choice for the final dimension. This leads to tabu
or tabu X columns, which measures each cell natural width
at first, and then computes the widths. I think such a feature
is beyond the scope of siunitx for:
1) computing the tabular 2 times slows down compilation
2) the tabular body has to be collected
3) the feature is related to tabulars and not to numbers.
(this is my idea about tabu X[3mc]{S[per-mode=fraction]}
preamble. And I think it requires some algorithm
like the ones impolemented in tabu/tabularx)

Well an option such as S[column-width] could provide , i think, a mean
to set a fixed width, which would be sufficient in most of the
"real life" cases, without too much sacrifice to efficiency.

Working thing through in my mind, I suspect you are correct. (For much
the same reason there is no automated way to do an asymmetric
alignment of S column material. I've though about it, but you need to
know how much space to reserve, and that's only known at the end of
the column or if the user tells you at the start.)
--
Joseph Wright
.

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