bugs about math blocks in markdown environment

[yfzhao20]

Hi! When I use $$...$$ (math blocks) in markdown environment, it gives me a thousand bugs😂 like that:

Here is my file:

\documentclass[UTF8]{ctexart}
\usepackage[hybrid]{markdown}
\usepackage{amsmath}
\begin{document}
\begin{markdown}
$$
\begin{aligned}
\cos^n\theta&=\left(\frac{e^{i\theta}+e^{-i\theta}}{2}\right)^n\\
&=(\frac{1}{2})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}e^{i\theta(n-2m)})\\
&=(\frac{1}{2})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}\frac{e^{i\theta(n-2m)}+e^{-i\theta(n-2m)}}{2})\\
&=(\frac{1}{2})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}\cos(n-2m)\theta)\\
\sin^n\theta&=\left(\frac{e^{i\theta}-e^{-i\theta}}{2i}\right)^n\\
&=(\frac{1}{2i})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}e^{i\theta(n-2m)}(-1)^m)\\
&=(\frac{1}{2i})^2(\sum\limits_{m=1}^{n}\tbinom{n}{m}\frac{e^{i\theta(n-2m)}i^{2m}+e^{i\theta(2m-n)}i^{2(n-m)}}{2})\\
&=(\frac{1}{2})^n(\sum\limits_{m=1}^{n}\tbinom{n}{m}\frac{e^{i\theta(n-2m)}(-i)^{n-2m}+e^{-i\theta(n-2m)}i^{n-2m}}{2})\\
&=(\frac{1}{2})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}\frac{e^{i(\theta-\frac{\pi}{2})(n-2m)}+e^{-i(\theta-\frac{\pi}{2})(n-2m)}}{2})\\
&=(\frac{1}{2})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}\cos(n-2m)(\theta-\frac{\pi}{2}))\\
\end{aligned}
$$
\end{markdown}
\end{document}

however if I only keep the first two lines of my math formula, everything will be okay:

\documentclass[UTF8]{ctexart}
\usepackage[hybrid]{markdown}
\usepackage{amsmath}
\begin{document}
\begin{markdown}
$$
\begin{aligned}
\cos^n\theta&=\left(\frac{e^{i\theta}+e^{-i\theta}}{2}\right)^n\\
&=(\frac{1}{2})^n(\sum\limits_{m=0}^{n}\tbinom{n}{m}e^{i\theta(n-2m)})\\
\end{aligned}
$$
\end{markdown}
\end{document}

The code of math block should be okay because I have tested it in Markdown editor. It should be displayed like this:

What's the matter? Is it the bug of markdown package, or my fault?🤔

by the way: I find only \\\\ can give me correct line break in math block but not \\, even I open "hybrid".

Thanks!!

[Witiko]

@yfzhao20 I am sorry to hear about your trouble. It's best to drop out of markdown before math blocks:

\documentclass[UTF8]{ctexart}
\usepackage[hybrid]{markdown}
\usepackage{amsmath}
\begin{document}
\begin{markdown}
Here is a formula:
\end{markdown}
$$
\begin{aligned}
\cos^n\theta&=\left(\frac{e^{i\theta}+e^{-i\theta}}{2}\right)^n\\
... trimmed for brevity
\end{aligned}
$$
\begin{markdown}
Let's talk about something else ...
\end{markdown}
\end{document}

As you have noticed, \\ and _ will get interpreted by Markdown as \ and the beginning of emphasized text, respectively. You can disable the interpretation of _ by specifying the underscores=false option, but you still have to write \\\\ for \\.

I am closing this issue as a duplicate of #61. Please, feel free to direct further questions and ideas there.

[yfzhao20]

Ah! It works after I let underscores=false✅. But I still have to write \\\\ for \\ . Thanks🎉!