# Dividing two vectors of different sizes

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Aleem Andrew on 15 Mar 2021
Commented: Matt J on 15 Mar 2021
If you have two vectors a = [1 2 1]; b = [1 1] that represent polynomials can you divide a by b to get [1 1] as the answer, since (s^2+2s+1)/(s+1) = s+1? I know you can divide the vectors by first converting them to polynomials using poly2sym(a)/poly2sym(b) and then extract the coefficients but is there a simpler way?
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### Accepted Answer

Matt J on 15 Mar 2021
Edited: Matt J on 15 Mar 2021
Yep. Just use deconv.
deconv([1,2,1],[1,1])
ans = 1×2
1 1
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Aleem Andrew on 15 Mar 2021
Can you divide vectors with deconv or a similar method if the numerator's degree is smaller than the denominator's? I get the incorrect answer 0 when I do so instead of the equivalent of (s+3)/(s^3+17s^2+14s+8).
numg=[1 3]; deng=[1 7 14 8];
deconv(numg,deng)
Matt J on 15 Mar 2021
What do you think the result should be?

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