margin bode plot lines wrong when 'TimeUnit' not seconds

Hi All,

Given a system with units not in seconds, the margin command does not show the gain or phase margins correctly in the bode plot. For example:

   sys = tf([2 1 3 4],[1 2 3],'TimeUnit','minutes')
  margin(sys)

In this example you can see that the vertical line marking the phase margin does not extend down from the 0dB crossing on the magnitude plot. Likewise, the vertical line marking the gain margin does not originate at the 180degree crossing.

Is there a problem with how I have defined the system, or is this a bug with margin?

Regards,

Jamie

Answer 1

[Craig]

This is a bug in the drawing of the margin lines when the units are not in seconds. I have created a bug report for it.

Thanks, -craig