zoom
display('Select zoom in on IY to select quasi period');
pause;
[xcoord, ycoord] = ginput(5);
xcoord = round(xcoord);
IY_per_n(1) = abs(xcoord(1)-xcoord(2));
IY_per_n(2) = abs(xcoord(2)-xcoord(3));
IY_per_n(3) = abs(xcoord(3)-xcoord(4));
IY_per_n(4) = abs(xcoord(4)-xcoord(5));
IY_per_n_avg = mean(IY_per_n)
IY_per_t_avg =  IY_per_n_avg / FSdec
IY_freq_avg = 1 / IY_per_t_avg
