elems

// create a symbolic vector
v = %(Vec("x",5))

// add "x1" as last element to v
v: "x1"

// create a symbolic set with (unique) elements of v
S = %(Set(v))

// create a matrix with diagonal v
M = %(Diag(v))

// number of elements in v, S, and M
elems(v)
elems(S)
elems(M) 

// clean up
reset();
clear v S M;