Re: Math alignment problem

[Aditya Mahajan <adityam@umich.edu>]

On Tue, 20 Jan 2009, Marcin Borkowski wrote:

> Dnia Sat, Jan 10, 2009 at 07:14:58PM -0500, Aditya Mahajan napisał(a):
>>>> On Sat, 10 Jan 2009, Marcin Borkowski wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I'd like to typeset a system of simultaneous equations.  I want it to
>>>>> have a brace on the left (like "cases"), but inside I want it to have
>>>>> two columns aligned like "align".  Also, I'd like to have the vertical
>>>>> space between the equations be small (like in cases), not so big as in
>>>>> align.
>>>>>
>>>>> How to do this?
>
> (answers cut)
>
> Thank you very much.  But one thing still puzzles me: the vertical
> distance between the cases.  How to increase it?  (Shouldn't there be a
> parameter for this?  But I couldn't find one...)

For matrix, the current definition works hard so that you cannot change 
vertical distance. For simultaneous equations, you need a math strucutre 
which ConTeXt does not provide.

>From what I understand amsmath hasthere are three kinds of math 
"strucures"

1. Outer display structures (equation, align, gather, and multline)
2. Inner display structures (aligned, gathered, and multlined (provided by 
mathtools package))
3. Inner inline structures (matrix, cases, etc).

The first two display structures have \displaystyle set and have "loose" 
spacing. The last inline structure has no \displaystyle set and has 
"tight" spacing. So, what you need for simultaneous equations is something 
from class 2 with the ability to put a brace on the left (empheq package 
in latex allows you to do this with aligned, etc).

Currently, ConTeXt does not provide anything of class 2. It is easy to 
provide it (one just needs to copy the definitions of mathalign but not 
set the width of hbox to be textwidth), but everytime I start working on 
it I get distracted by the bigger problem---ConTeXt is not as good as it 
can be for outer display.

Aditya
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