[FIXED] iPython notebook won't convert to PDF when using align

Issue

If I have an iPython notebook, and a cell contains an align statement, as in the following:

$$
\begin{align}
x &= 3 \\
y &= 4
\end{align}
$$

Then running ipython nbconvert test.ipynb --to pdf gives me the following error:

! Package amsmath Error: Erroneous nesting of equation structures;
(amsmath)                trying to recover with `aligned'.

See the amsmath package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.233 \end{align}

? 
! Emergency stop.
 ...                                              

l.233 \end{align}

!  ==> Fatal error occurred, no output PDF file produced!
Transcript written on notebook.log.

I can't find notebook.log anywhere. Where is it located, and, more importantly, why is align breaking my PDF conversion? I have amsmath installed!

Solution

@moose was right: you should have both the $$ ... $$ and align notation combined. Pick one of the two.

That is, for multiline equations, use:

\begin{align}
x &= 3 \\
y &= 4
\end{align}

And for single-line equations, use:

$$
x = 3
$$

Answered By - Nick Sweet