You'll need to build octave, and include the option "--enable-64" when you run configure.
Before doing that, do have you enough RAM for a double vector of length = 15.36G? You'll need 122.88 GBytes of RAM
just for your vector.
This is the RAM I have : I don't understand if that is enough. And if so, not sure how octave is built.
total used free shared buffers
cached
Mem: 3022 1539 1482 0 173 728
-/+ buffers/cache: 637 2384
Swap: 1951 0 1951
Asha G