> Why can't you just write arr.{j,i,k} instead of arr.{i,j,k} ?

No it is really the ordering of the data which changes, let's see an example:

In the library I use the elements are ordered like this in the 1dim C array:
01  02  03  04  05  06
07  08  09  10  11  12
13  14  15  16  17  18
19  20  21  22  23  24

but with the c_layout of big array the datas are ordered like this :
01  05  09  13  17  21
02  06  10  14  18  22
03  07  11  15  19  23
04  08  12  16  20  24


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