If you look at the size of a matrix

`X = rand(3,4)`

`size(X)`

You will see that it is of size 3×4. However, when you look at the size of` X(:,1,:)`

it is * not* a matrix but a three-way array of size 5x1x61.

Thus, we can easily see that it is in fact a 5×61 matrix, but MATLAB sees it as a three-way array where one of the ways/modes is of dimension 1.

So in order to be able to plot this actual matrix held in a three-way array, the three-way array must be converted to matrix.

The function

`squeeeze `

will do this (type `help squeeze`

)