I tried to compile something like the following but it is not compiling:
$$
\begin{array}{ccc}
[u,v]=0&,&\text{if bla}\\
[u,v]=0&,&1
\end{array}
$$
I also tried
\begin{eqnarray}
[u,v]=0&,&\text{if bla}\\
[u,v]=0&,&1
\end{eqnarray}
I'm using pdflatex (Windows prompt), Version 3.1415926-1.40.10 (MiKTeX 2.8), and the compiler shows
! Missing number, treated as zero.
(to be read again)
u
1.45 [u,v]
=0 &,&1
?
Sincerely, this makes no sense for me and if I delete the "]" in the second line, or if I don't use the second line in the eqnarray (or array), it compiles normally.
{}[as otherwise the[is taken as the optional argument to\\also don't use$$in latex (this is a duplicate, I'll add a link in a bit) – David Carlisle Nov 12 '13 at 22:56arrayenvironment; Error with table; [“” as first character in table row – Werner Nov 12 '13 at 23:00