n = size(M,1) returns the number of
key-value pairs in the input Map object.
size(M,1) is equivalent to length(M) and
to the property M.Count.
szdim = size(M,dim)
returns the length of dimension dim. Since a
Map object stores data as an
n-by-1 set of key-value pairs,
size returns 1 when dim >
1.