mailing-list for TeXmacs Users

[Adam Warner <address@hidden>]

On Mon, 2002-02-18 at 18:05, Phil Mendelsohn wrote: 
> On Mon, Feb 18, 2002 at 04:52:16PM +1300, Adam Warner wrote:
> > So the formatting looks like this:
> > 
> >     y=a*(b+c)
> >      =ab+ac
> > 
> > One way to approximate this is to use a table which leads to the
> > formatting looking something like this:
> > 
> >     y = a*(b+c)
> >       = ab+ac
> > 
> > but the spacing between the = sign is too large.
> 
> Using Insert > Math > Equation_s_ (note the 's') will give you what
> you want.  Type the first part of your eqn, then CTRL-f, for the
> middle column of what's analogous to LaTeX's {eqnarray} environment,
> then CTRL-f again when you want the third column.

Unfortunately eqnarray is like using a plain table. Specifically it
leaves too much space between the LHS and RHS of the equation and the =
sign (middle operator). This looks out of place when a standard equation
has no such extra spacing. This is for example recognised by some who
use AMS-LaTeX <http://www.stat.umn.edu/~charlie/amslatex.html>: "Spacing
around equals signs matches the normal spacing in the equation
environment (unlike eqnarray)". 

So I set about editing eqnarray in basic.ts to eliminate this extra
spacing (trial and error at first and then I found this critical piece
of information: http://alqua.com/tmresources/internal%20table%20markup).
The result is an equation with spacing that looks very similar to a
standard non-tabular equation. This is the original piece of
<assign|eqnarray*>: 

<cwith|1|-1|1|1|cell lsep|0spc>|<cwith|1|-1|-1|-1|cell rsep|0spc> 

And this is the replacement:

<cwith|1|-1|2|2|cell lsep|-0.15fn>|<cwith|1|-1|2|2|cell rsep|-0.15fn>

What this does is reduce the left and right margins around the second
(centre) cell by -0.15fn.

After this change you will not see the difference between a one line
equation and a one line eqnarray.


The second improvement is a new equation definition by allowing LHS
and/or RHS pieces of mathematics on the same line:

Columns:
1                                2 3 4                               5
(x)                            y(x)=a+bx                     x\in{0,1}

This new macro definition achieves this:

  <assign|fivecoleqnarray*|<macro|body|<with|paragraph 
mode|center|mode|math|formula
  style|true|<surround|<format|no page break
  before><vspace*|0.5fn>|<vspace|0.5fn><format|no indentation
  after>|<tformat|<twith|table hyphen|y>|<twith|table
  width|1par>|<twith|table min cols|5>|<twith|table max
  cols|5>|<cwith|1|-1|3|3|cell lsep|-0.15fn>|<cwith|1|-1|3|3|cell
  rsep|-0.15fn>|<cwith|1|-1|1|-1|cell bsep|0sep>|<cwith|1|-1|1|-1|cell
  tsep|0sep>|<cwith|1|-1|1|1|cell hpart|1>|<cwith|1|-1|-1|-1|cell
  hpart|1>|<cwith|1|-1|1|1|cell halign|l>|<cwith|1|-1|2|2|cell 
halign|r>|<cwith|1|-1|1|1|cell
  hyphen|b>|<cwith|1|-1|3|-3|cell halign|c>|<cwith|1|-1|-2|-2|cell
  halign|l>|<cwith|1|-1|-1|-1|cell halign|r>|<cwith|1|-1|-1|-1|cell 
hyphen|t>|<arg|body>>>>>>

You can add it to the TeXmacs menu by adding a line to main-menu.scm:

    (-> "mathematics"
        ("formula" "$" (make-with "mode" "math"))
        (if (style-has? "basic-style")
            ("equation" (make-big-expand "equation*"))
            ("equations" (make-expand-arg "eqnarray*"))
            ("5 column equations" (make-expand-arg "fivecoleqnarray*"))
            ("numbered equation" (make-big-expand "equation"))))

Then put the replacement basic.ts into the appropriate folder and
recompile the program (./configure && make and make install as root).

To improve the centring of columns 2,3,4 I'd like to be able to
automatically set the width of columns 1 and 5 equal to the width of the
widest column. This should stop the entering of column 1 or column 5
maths moving the 2,3,4 cells to the right or left respectively. If
someone could give me some pointers how to achive this I'd appreciate
it.

It would work like this:

Columns:
1                                2 3 4                               5
                               y(x)=a+bx                    1234567890

\___  ___/                                                  \___  ___/
    \/                                                          \/
Width of column 1: 0                             Width of column 5: 10
Width col 1 < width col 5
Thus set width of column 1 to 10

(and vice versa if column 1 is wider than column 5)

Regards,
Adam