initializing matrix not from the first row

[Sergei Steshenko]

Hello,

in octave-3.6.2 I see this:

"
octave:1> foo(2, :) = [1 2 3]
foo =

   0   0   0
   1   2   3

octave:2> 
".

I have no problem with the fact that the matrix has two rows - since I've
initialized row #2, row #1 is somehow created.

My question is: why row #1 is all zeros ? And not NaNs ? Compatibility with
Matlab ?

Thanks,
  Sergei.