A plot of 
against 
is shown in figure 7,
showing strong evidence for the existence of a pole at the origin. The
parameter 
of equation 7 is equal to 
,
corresponding to 
.
Figure 7: Periodogram (dots) and fitted spectrum (grey curve) of the form in
equation 7, for M = 100 and 60% load. The graph shows
strong evidence for a pole at the origin.