Uwe Stöhr wrote: > > It looks like someone spent some effort not to output &'s if they are > > not necessary.
André: http://www.lyx.org/trac/changeset/5004 > > Why would it be more correct to output all &'s ? Isn't it > > much cleaner not to output them ? > > It is not clean and even wrong. That we not output the column separators > causes the bug we have. Equations are in general arrays that have for every > row the same number of columns. What we currently output is an array where > one row doesn't have any column and this is wrong. As I understand it, '&' only indicates a column jump, it does not define the number of columns, so it's not mandatory if cells don't need to be accessed. Thus \begin{tabular}{ccc} a & b & c\tabularnewline & & \tabularnewline d & e & \tabularnewline \end{tabular} and \begin{tabular}{ccc} a & b & c\tabularnewline \tabularnewline d & e \tabularnewline \end{tabular} or \begin{array}{ccc} 1 & 2 & 3 \\ & & \\ 4 & 5 & \end{array} and \begin{array}{ccc} 1 & 2 & 3 \\ \\ 4 & 5 \end{array} are equal. IMHO (but I'm not a math user) it's just a matter of style whether the '&' are output or not in the given cases. I've looked into some math manuals (such as http://tug.ctan.org/get/info/math/voss/mathmode/Mathmode.pdf), and omitting the '&' seems frequent practice. However, I think our current LaTeX output can be improved anyway. I think new rows should always be started on a new line. I.e., \begin{align*} a & = & b & = & c\\ \\ x & = & y & = & z\end{align*} not \begin{align*} a & = & b & = & c\\ \\x & = & y & = & z\end{align*} As to the proposed patch, I'd like to hear the opinion of math users. In any case + return " & " + eol; should be + return from_ascii(" & ") + eol; There are some other cases in InsetMathGrid, where conversion from string to docstring is missing. Jürgen
