[OS X TeX] Missing $ inserted in a "variations" environment

[Alain Schremmer]

On Mar 15, 2009, at 5:13 PM, Ross Moore wrote:

> Hi Alain,
>
> On 16/03/2009, at 7:56 AM, Alain Schremmer wrote:
>
>> On Mar 15, 2009, at 4:24 PM, Peter Dyballa wrote:
>>
>>>  discipline like you demonstrated
>>
>> You really ought NOT to make fun of your elders.
>>
>>> or uses GNU Emacs, which in AUCTeX mode colourizes the & in red.
>>
>> Forget THAT.
>
> I think we need a few smileys here.
>  :-)

They went absolutely without saying but you are just as absolutely  
right and, of course, I apologize should anyone have thought I was  
not joking. (But what I don't understand is how everyone except me  
seems to know when Dyballa is joking. :-)) But then, it should be  
rather obvious that I have no sense of humor whatsoever—and I am not  
joking.)

> What Peter was saying, and Jonathan has implied, is that if
> you use the coding:
>
> %\noindent \makebox[\textwidth][c]{
>  \begin{variations}
>    x  & \mI  &   & \alpha& & & 1 & & \beta&  & & 2 & & \pI & \\
>    \filet
>  f'(x) & \bg & + & \bb&  & + & \z & -& \bb & & - &\z& + & &\bd \\
>  \filet
>   \m{f(x)} & \bg \mI &  \c \h{\pI} & \bb& \mI & \c & \h{-1} & \d  
> \mI & \bb
> & \h{\pI}& \d &\frac{3}{2}& \c
>   & \h{\pI} & \bd \\
> \end{variations}
> %}
>
> then error messages become more meaningful.
> Note the comment characters before the \noindent and '}'.
> These are essential.
>
> The reason is that \makebox reads its full argument; ie. down to '}'
> before processing any of the commands it contains.
> Thus if an error or warning occurs, then TeX reports it as
> occurring at the line number where it has read to --- namely
> at the end, where '}' occurred.
>
> By removing that \makebox (using comments, since presumably
> we'll need it back again after having debugged the problem)
> then TeX is reading and interpreting contiguously.
> Hence when an error occurs, the messages will identify the
> correct place within this tabular material.
>
>
> This is generally a better debugging technique than inserting
> extra stuff within the output, using iXXXX as has been suggested.
> The latter works here, but only because TeX isn't too confused
> by the particular error. In other circumstances you may get
> no output at all, so  iXXXX  would leave you none the wiser.
>
> Hope this helps,

This is going in the very special folder where I put the stuff that I  
need a bit of time to study. And that is dead serious.

Grateful reagards
--schremmer