View source for Ziegler-Nichols tuning rules don't quite match the original gains from the Ziegler-Nichols paper

{{Errata
|Book edition=Second
|Version number=3.0j
|Submission date=31 Aug 2019
|Your name=Richard Murray
|E-mail address=murray@cds.caltech.edu
|Chapter number=11
|Page number=11-12
|Line number=8
|Current status=Closed
}}
The gains listed for the original Ziegler-Nichols tuning rules don't quite match what was in the original paper: 

* For the step response method, the integral time constant for a PI controller should be T_i = \tau/0.3 (instead of 3 \tau).

* For the frequency response method, the proportional gain for a PI controller should be k_p = 0.45 k_c (instead of 0.4 k_c and the integral time constant should be T_i = T_c/1.2 (instead of 0.8 T_c).