From: Jane on

The original array is 18x90.

I take from this data:
(1:18,1:3:90)
(1:18,2:3:90)
(1:18,3:3:90)

which equals the sizes
C1 =18x30
C2 =18x30
C3 =18x30

After transposing D is equal 30x54 as (1:3:90 = 30) and (3 * 18 = 54).

This means that 30 * 3 values are taken from row one of the original data and then transposed and then this becomes one set of data (consisting of 3 columns). Then next to those 3 columns there is another three columns which is equal to the second row down of the original data (after taking the 3 values from every column of the original data for that particular row).

I am not sure I understand nested permute, transpose etc.