gitbook editor kaTex expected comma after expression

Question

This is the error information:

The following is my book.json:

{
    "plugins": ["katex"]
}

The following is my error file:

I just can't figure out what's wrong with the math expression.

Answer 1

It looks like the math expression is ok, at least it works perfectly with KaTeX for browsers

$$S_{N_k}={{E(N_k-\mu_{N_k})^3 }\over {\sigma _{N_k}^3}}$$

I'm not familiar with gitbook, but I can suggest at least this: while you have

$$S_{N_k}={{E(N_k-\mu_{N_k})^3 }\over {\sigma _{N_k}^3}}$$,

it is usually suggested that the comma is inside the formula (may be gitbook requires that as a good practice), so try:

$$S_{N_k}={{E(N_k-\mu_{N_k})^3 }\over {\sigma _{N_k}^3}},$$