Conversion from Mathematica to Matlab

Hi there. I am trying to convert a piece of code from Mathematica to Matlab. The code is given in the picture. In the mathematica code snippet, there is a section where it defines:

st= FindRoot[V[s] == em, {s,em}][[1,2]]

I am unsure, what is the double sqaure brackets at the end of the expression, [[1,2]]? I have never seen this before nor am I familiar with mathematica. The attached file gives a better idea of what I am asking about. Thanks.

Answer 1

[Walter Roberson]

In Mathematica, [[1,2]] is indexing at location (1,2); see https://reference.wolfram.com/language/tutorial/ManipulatingListsByTheirIndices.html

In context, they are expecting multiple roots and are extracting the second root.