($) last index
The $ symbol denotes the last index (row or column) of the array. It is therefore equal to the number of rows or columns.
The $ symbol is also used to LaTeX texts, which must start and end by $. See also math_rendering_features_in_graphic.
a=[1,2,3;4,5,6];
a($)
b = [1 2 3;4 5 6;7 8 9];
// Access the last element of first row, i.e. 3
b(1,$)
// Access the last element of second column, i.e. 7
b($,2)
//Access the last element of b, i.e. 9
b($,$)
// Add a row at the end of the matrix b
b($+1,:) = [1 1 1]
// The $ symbol as a LaTeX delimiter
`titlepage`_(['$\Huge\textrm{It is }\LaTeX:$';'$\Huge 2^2+1=\sqrt{25}$'])