PA_data = PHASE_ANGLE(angle) determines the Phase Angle for a single kinematic waveform using the Hilbert transform method. ARGUMENTS r : n x 1 array. Kinematic data represent angle (joint or segment) RETURNS PA_data : n x 1 array. Phase angle computed on input angle using the Hilbert transform NOTES See Lamb and Stöckl "On the use of continuous relative phase: Review of current approaches and outline for a new standard". Clin Biomech 2014 https://doi.org/10.1016/j.clinbiomech.2014.03.008