# How to chnage the coefficent for transfer function?

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Shambaven Srimurugathas on 4 Feb 2024
Commented: Sam Chak on 7 Feb 2024
How do I change the 'deng' coefficient where it shows (s+11.17)(s+10.89)(s^2+0.033s+0.553) at the end. Trying to figure out but been stuck. Let me the changes need to made ASAP:

Sam Chak on 5 Feb 2024
Edited: Sam Chak on 7 Feb 2024
I believe that the following result is probably what you are seeking.
Update 2: As per what you want.
numg = conv([1 0.37], [1 2.26]);
deng = [ 1, 22.093, 122.92228, 16.2133429, 67.2676389];
K = -8;
G = zpk(K*tf(numg, deng))
G = -8 (s+2.26) (s+0.37) ------------------------------------------ (s+11.17) (s+10.89) (s^2 + 0.033s + 0.553) Continuous-time zero/pole/gain model.
Update 1: There is probably a typo in the denominator in your original code.
numg = [-0.37, -2.26];
% deng = [ 1, 22.093, 122.92228, 16.2133429, 6.72676389]; % <-- there is probably a mistake here
deng = [ 1, 22.093, 122.92228, 16.2133429, 67.2676389];
K = -8;
% G = zpk(numg, deng, K)
G = zpk(K*tf(numg, deng))
G = 2.96 (s+6.108) ------------------------------------------ (s+11.17) (s+10.89) (s^2 + 0.033s + 0.553) Continuous-time zero/pole/gain model.
Shambaven Srimurugathas on 7 Feb 2024
Thx for your help but the bottom dnominator coefficient is right but I want the top to show as -8(s+0.37)(s+2.26). If you know how to fix that I appreciate it.
Sam Chak on 7 Feb 2024
Take a look at Update 2 above. If you find the solution helpful, please consider clicking 'Accept' ✔ on the answer and voting 👍 for it. Thanks a bunch! By the way, you should also vote for other helpful answers as tokens of appreciation.

Hassaan on 4 Feb 2024
% Define the coefficients for the denominator polynomial
deng = [1, 22.093, 122.92228, 16.2133429, 6.72676389];
% Assuming numg and K have been defined correctly as before
numg = [-0.37 -2.26];
K = -8;
% Create the zero-pole-gain model
G = zpk(numg, deng, K);
zpk with properties: Z: {[2×1 double]} P: {[5×1 double]} K: -8 DisplayFormat: 'roots' Variable: 's' IODelay: 0 InputDelay: 0 OutputDelay: 0 InputName: {''} InputUnit: {''} InputGroup: [1×1 struct] OutputName: {''} OutputUnit: {''} OutputGroup: [1×1 struct] Notes: [0×1 string] UserData: [] Name: '' Ts: 0 TimeUnit: 'seconds' SamplingGrid: [1×1 struct]
-----------------------------------------------------------------------------------------------------------------------------------------------------
If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.
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Shambaven Srimurugathas on 4 Feb 2024
Unfortunately its not what I want. I need to change the 'deng' coefficient say that (s+11.17)(s+10.89)(s^2+0.033s+0.553) when I run the code.
Hassaan on 4 Feb 2024

Star Strider on 4 Feb 2024
What do you want to change it to?
The displayed result is the format that the zpk function produces. If you want them otherwise, omit the zpk call, and just multiply the numerator by -8.
Walter Roberson on 4 Feb 2024
Or convert the zpk to a transfer function by using tf()

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