function procTracks = linearisePhi(procTracks)
%LINEARISEPHI takes the phi field of the input version of procTracks
%(defined nematically, so between -90 and 90) and adds or subtracts
%increments of 180 to each position in the track to ensure phi keeps track
%of a single pole.
%
%   INPUTS:
%       procTracks: The output of the tracking module of FAST, stored in
%       the 'Tracks.mat' file.
%
%   OUTPUTS:
%       procTracks: Version of procTracks with a new 'fullPhi' field, which
%       contains the wrapped version of phi.
%
%   Author: Oliver J. Meacock, (c) 2019

for i = 1:size(procTracks,2)
    phiDiff = diff(procTracks(i).phi);
    stepsUp = phiDiff < -90;
    stepsDown = phiDiff > 90;
    intSteps = cumsum(stepsUp - stepsDown);
    intSteps = [0; intSteps];
    procTracks(i).fullPhi = procTracks(i).phi + intSteps*180;
end