Correct behavior of common_size()?

[Robert T. Short]

When I include an empty vector in common_size() I get, for example,

octave> [ec,x,y,z]=common_size([],1,[1 2 3])
ec =  1
x = [](0x0)
y =  1
z =

   1   2   3

In other words, I get an error because the empty matrix can't be sized 
to match the other elements.  I wonder if this is the correct behavior, 
though.  It is not clear to me what *should* happen and there is 
probably a good reason for the current approach, but in addition to the 
current behavior one of two possibilities comes to mind:

ec = 0
x = [](0x3)
y = [1 1 1]
z = [1 2 3]

or

ec = 0
x [] (0x0)
y = [1 1 1]
z = [1 2 3]

Thoughts?  Or maybe this is just a case of educating Bob?  BTW, if a 
change needs to be made I am volunteering but I need to be clear on the 
concept first.

Bob