MATLAB: Is Varying Transfer Function description wrong

Control System Toolboxsimulinkvarying transfer function

In Varying Transfer Function (https://www.mathworks.com/help/control/ref/varyingtransferfunction.html) settings dialog showed the following equation:
             b0 + b1 s + ... + bN s^N 
  H(s) = -------------------------------- 
               a0 + a1 s + ... + s^N
This equatin also showed as block image.
But in block help article it says:
             b0 + b1 s + ... + bN s^N 
  H(s) = -------------------------------- 
               1 + a1 s + ... + aN s^N
I think the second formula is correctly describing this block, but in both cases I can't set one coefficient in denominator. Is there a way to set all coefficients in denominator?

Best Answer

You can take a0 common and make the first coefficient 1. from this you can set all the coefficient and then multiply the whole block by (1/a0).
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