This is similar to str, but it shows data at the first and
last of the vector, which can be quite helpful in debugging.
vectorShow(v, msg, digits = 5, n = 2L)the vector.
a message to show, introducing the vector. If not provided, then
a message is created from v.
for numerical values of v, this is the number of digits
to use, in formatting the numbers with format; otherwise,
digits is ignored.
number of elements to at start and end. If n
is negative, then all the elements are shown.