I understand that you are trying to insert an equation in a Live Script and you are trying to use the LaTeX commands matrix and pmatrix to insert matrices in this equation.
From what I understand, as of MATLAB R2016a, equations in LaTeX only support basic TeX math mode commands. The matrix syntax using begin keyword and \\ operators, which is derived from the amsmath package cannot be used in Live Editor.
However, you can use the following syntax for generating a matrix:
A = \pmatrix{1 & 2 \cr 3 & 4}
This will generate an equation which looks like this:
Same syntax can also be used with matrix to generate a matrix which is not enclosed in parantheses.
I realize that this is not clear from the documentation. I work for MathWorks and I have provided this feedback to the appropriate team.
