periodogram format question

[jp d]

hi,
dumb question,
what wrong with this?

a = [-1,-1,-1, 2,-1,-1, 2, 1, 1;
 2, 2,-1,-2,-1, 2,-2, 1,-1,;
-1, 1,-2, 1, 1, 1, 2,-2, 1;
 2,-1,-1,-1, 1,-1,-2, 1, 1;
-1,-2,-1,-1,-1,-1, 2,-1, 2;
 2,-2,-2,-1, 2, 1, 2,-2,-1;]

periodogram(a)

i get these errors:

error: operator -: nonconformant arguments (op1 is 6x9, op2 is 1x9)
error: evaluating binary operator `-' near line 41, column 25
error: evaluating argument list element number 1
error: evaluating argument list element number 1
error: evaluating binary operator `.^' near line 41, column 39
error: evaluating binary operator `/' near line 41, column 44
error: evaluating assignment expression near line 41, column 10
error: called from `periodogram' in file 
`/usr/share/octave/3.0.5/m/signal/periodogram.m'
error: near line 8 of file `negnotyet.dat'

thanks
jpd