length on a matrix

[Carlo Rossi]

Hello,
simple question:
I did a matrix in this way:
test = [ test1(1:4, :); test2(1:4, :); ];

and after I like to know the number of the rows:

length(test);

but it returns '2'.
in fact, I use
size(test)
the number correct '8' is returned.

Could anybody tell me why length doens't work?
thanks,