MATLAB: How to enter a transfer function without writing down the exponents

exponentialMATLABsystransfer functionwriting out exponents

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?

Best Answer

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
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