Explanation of the code sequence

Given that T=zeros(100,100,10) and I want to understand this sequence T(1,:,9)

Answer 1

[Walter Roberson]

T(1,:,9)

is the same as T(1,1:end,9) which is the same as T(1,1:size(T,2),9)

This says to take the combination of row 1, all columns, hyperpane #9, of T. The result will be size 1 by 100 by 1, which MATLAB will refer to as being 1 by 100 because it does not bother to keep track of trailing dimensions of length 1

Answer 2

[Star Strider]

The notation ‘T(1,:,9)’ will return the first row, and all columns, in the 9th ‘page’ of ‘T’. (The third dimension is characteristically referred to as the ‘pages’ of a 3D matrix.)