# Too long LaTex formulae not shown in comments?

If you try to show this formula in comments, it fails.

$$M:\left[\begin{array}{cc}x&y\end{array}\right]\mapsto\left[\begin{array}{ccc}x&y&1\end{array}\right]M=\left[\begin{array}{ccc}u&v&w\end{array}\right]\mapsto\left[\begin{array}{cc}\frac{u}{w}&\frac{v}{w}\end{array}\right]$$

Source here.

• Example $$M:\left[\begin{array}{cc}x&y\end{array}\right]\mapsto\left[\begin{array}{ccc}x&y&1\end{array}\right]M=\left[\begin{array}{ccc}u&v&w\end{array}\right]\mapsto\left[\begin{array}{cc}\frac{u}{w}&\frac{v}{w}\end{array}\right]$$ – hhh Sep 14 '12 at 1:22
• – Martin Sleziak Jun 2 '15 at 19:34

In comments, as in chat, when a string has more than 80 characters without whitespace, the editor adds whitespace (\unicode{x200C}\unicode{x200B} Zero Width Non-Joiner, Zero Width Space). If you get lucky, the whitespace is added in a place where it does not cause a problem. However, most of the time, it breaks a keyword, control sequence, etc and corrupts the LaTeX.
• Let's see if this works with spaces forced in good places $$M:\left[\begin{array}{cc}x&y\end{array}\right] \mapsto\left[\begin{array}{ccc}x&y&1\end{array}\right] M=\left[ \begin{array}{ccc}u&v&w\end{array}\right] \mapsto\left[\begin{array}{cc}\frac{u}{w} &\frac{v}{w}\end{array}\right]$$ – robjohn Sep 14 '12 at 2:34