splitting array based on negative and positive values

[Rick T]

Greetings All

I have and array and I'm trying to split out rows based on the positive and negative values in the 3rd column into their own separate arrays
I know I can do a sortrows on the 3rd column but how does one split out rows based on the the negative and positive values of the 3rd column into there own array.

Example of array:
1,2,-3
2,3,4
5,6,-7
8,9,-10
11,12,13

1st array split
1,2,-3
5,6,-7
8,9,-10

2nd array
2,3,4
11,12,13

I'm using Octave 3.2.4 running under ubuntu 10.04 64bit
Thanks