Fig. 16. The simplified analytic model (SAM) modified to use a piece-wise linear approximation of cosine (see Fig. 3) as the compass response function (upper line) fitted using least sum of squared error to data (diamonds; Müller and Wehner, 1988) taken from fig. 11a in Hartmann and Wehner (1995). The lower line shows the correct homing angle. The value of the time constant obtained is =38.00. The fit is noticeably poorer than that obtained with the cosine-shaped compass sensor response function (see Fig. 11A). The axes are labelled as in Fig. 11.