Description of problem:
filter() function does not accept an initial state


Version-Release number of selected component (if applicable):
octave-3.4.3-1.fc16.x86_64


How reproducible:
every time


Steps to Reproduce:
1. run octave
2. in octave:
octave:3> a=1;
octave:4> b=ones(5,1)/5;
octave:5> [x IS] = filter(b,a,[1;zeros(10,1)],[])
octave:6> IS
IS =

   0
   0
   0
   0
octave:7> [x IS] = filter(b,a,[1;zeros(10,1)],IS);
error: filter: first dimension of SI must be of length max (length (a), length (b)) - 1

but
octave:7> max (length (a), length (b)) - 1
ans =  4

???

Expected results:

IS is the returned filter state and is the correct dimensions, but is not accepted as an input parameter


Additional info: