Format an array size for display.
Formats the given array size sz as a string for human-readable display. It will be in the format “d1-by-d2-...-by-dN”, for the N dimensions represented by sz.
sz is an array of dimension sizes, in the format returned by
Returns a charvec.
str = size2str (size (magic (4))) ⇒ str = 4-by-4