# Re: Equation Array

Thanks Paul, I've tried it but the first column is right aligned and
the third is left aligned. I'm kind of new on the subject and the
references I have from a friend make them left and right aligned,
respectively. Is there an standard way of aligning them?
-------------------------------------------------
Julio Rojas
jcredbe...@gmail.com


On Wed, Sep 2, 2009 at 5:11 PM, Paul A. Rubin<ru...@msu.edu> wrote:
> Julio Rojas wrote:
>>
>> Thanks, I've already done that, but no option seems to be of help. I'm
>> trying to put an integer programing model and every restriction should
>> be numbered and aligned like:
>>
>> Maximize Z                                          (1)
>> Subject to:
>> Z=sum(Xi)                                             (2)
>> Xi+Xj<=1                       for all i,j in P, i<j (3)
>> Xi,Xj in {0,1}                        for all i,j in P (4)
>>
>> So, some rows are numbered, the left column is left aligned and the
>> right column is right aligned. How can this numbered array be done?
>> -------------------------------------------------
>> Julio Rojas
>> jcredbe...@gmail.com
>>
>>
>>
>> 2009/9/2 Ignacio García <ignacio.gmora...@gmail.com>:
>>>
>>> Julio Rojas <jcredbe...@...> writes:
>>>
>>>> Dear all, is there a way to individually label some equations of an
>>>> equation array? Or some rows from an array?
>>>> -------------------------------------------------
>>>> Julio Rojas
>>>> jcredbe...@...
>>>>
>>> Please have a look at Help>Math (or Ecuaciones) where you can
>>> find a very fine description of this issue in the section 19,
>>> 19.3 and/or 19.4.
>>>
>
> Julio,
>
> Actually, I think what you want is in section 19.1.  Inside an equation
> array environment, Alt-m n toggles numbering of the entire array (separate
> number on each line), while Alt-m Shift-n toggles numbering of just the line
> the cursor occupies.
>
> BTW, I too write integer programs.  A while back I came across a reference
> to an article ("Avoid eqnarray!" by Lars Madsen, The PracTeX Journal #4,
> 2006) that claims that eqnarray is somehow evil.  The complaints are mainly
> about spacing (including the possibility that equation numbers are
> overwritten or crowded off the line).  He recommends AMS math environments
> or the mathenv package.  Then again, I came across a post on sci.op-research
> that as I recall advocated eqnarray.
>
> Anyway, here's an alternative I found somewhere:
>
> \begin{alignat*}{7}
>  & \text{maximize } & z= &  & 2x_{1} &  & + &  & 3x_{2} &  & + &  & 4x_{3}\\
>  & \text{subject to: } &  &  & 44x_{1} &  &  &  &  &  & + &  & 50x_{3} &
> \ge900\\
>  &  &  &  &  &  &  &  &  &  &  &  & \llap{\ensuremath{x_{1},x_{2},x_{3}}} &
> \ge0
> \end{alignat*}
>
> FWIW,
> Paul
>
>