How can I enter a transfer function without writing down the exponents?

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DdeR
DdeR 2018-10-25
编辑： DdeR 2018-10-25
Is there a possibility to enter transfer functions like this one:
without writing out the exponent?
I know that it could be inserted as:
num=[35 3.5 8.75];
den=[100 25 100.24 1];
sys=tf(num,den)
but writing out equations could be time consuming so is there a faster way?

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Stephan
Stephan 2018-10-25
编辑：Stephan 2018-10-25
Hi,
i think you made a mistake by multiplying the denumerator - When i calculate by hand i get:
num=[35 3.5 8.75]
den = [100 25 100.24 1]
For your purposes you could tryout conv function - it multiplies 2 polynomials:
num1 = [8.75];
num2 = [4 0.4 1];
den1 = [100 1];
den2 = [1 0.24 1];
sys = tf(conv(num1,num2),conv(den1,den2))
sys =
35 s^2 + 3.5 s + 8.75
------------------------------
100 s^3 + 25 s^2 + 100.2 s + 1
Continuous-time transfer function.
Best regards
Stephan

更多回答（1 个）

dpb
dpb 2018-10-25
num=8.75*[4 0.4 1];
den=conv([100 1]),[1 0.24 1]);
convolution of polynomial coefficient vectors is same as multiplication. NB: the hand multiplication above for the denominator is in error; the actual answer is
>> conv([100 1],[1 0.24 1])
ans =
100.0000 25.0000 100.2400 1.0000
>>

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