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Date:         Wed, 2 May 90 19:42:22 CET
Reply-To: LaTeX-L Mailing list <LATEX-L@DHDURZ1.uucp>
From: "Nelson H. F. Beebe" <Beebe@SCIENCE.UTAH.EDU>
Subject:      Blank lines in math, array, eqnarray, et al
To: Rainer Schoepf <BK4@DHDURZ1.uucp>
Status: R
X-Status: 
X-Keywords:                  
X-UID: 91

While helping a student solve some thesis formatting
problems yesterday, I was reminded of what I view as a LaTeX
design problem that might be possible to eliminate in your
redesign.

In TeX, white space (blanks, tabs, newlines) is ignored
almost anywhere, in the sense that 2 or more white space
characters are equivalent to 1 white space character.
However, in LaTeX, this is not true in math, array, and
eqnarray environments.

For example,

  \begin{eqnarray}
a & = & b + c \\
  & = & e + f
  \end{eqnarray}

formats without error, but

  \begin{eqnarray}

a & = & b + c \\

  & = & e + f

  \end{eqnarray}

generates a long sequence of confusing errors of the form:

! Missing $ inserted.
<inserted text>
                $
<to be read again>
                   \par
l.15

?
! Missing } inserted.
<inserted text>
                }
<to be read again>
                   $
<to be read again>
                   \par
l.15

?
! Missing } inserted.

...

I argue that array and eqnarray are inherently complex
environments, and it is important for the typist to be able
to freely format them for readability; otherwise the typein
can be very difficult to read.  While empty comment lines
can be used to get extra vertical separation to improve
readability, users often forget to do so, and the error
messages that arise from blank lines are not at all obvious
to non-expert users.

Also, in array and eqnarray, the \\ is already there to tell
LaTeX where the current row ends, so it seems that it should
be straightforward to skip whitespace following a \\.  In
the math environment, the situation may be more complex,
since there is no explicit \\, but it is still not obvious
why a blank line should generate an error.

Curiously, blank lines are harmless in tabular environments,
so I would argue there is `prior art' in LaTeX for
eliminating any special significance of blank lines (or \par
breaks, since I suppose that is what raises the error) in
math, eqnarray, array, and anywhere else they raise errors.

Comments, anyone?
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