PLV - phase locking value

Compute the Phase Locking Value between two signals across trials.

Compute the Phase Locking Value between two signals across trials, according to Lachaux, Rodriguez, Martinerie, and Varela (1999). The PLV value ranges from 0, indicating random phase differences, to 1 indicating a fixed phase difference.
See:
Lachaux, J. P., Rodriguez, E., Martinerie, J., & Varela, F. J. (1999). Measuring phase synchrony in brain signals. Human Brain Mapping, 8(4), 194–208.
http://www.ncbi.nlm.nih.gov/pubmed/10619414