Matlab Polynomial: Division and Multiplication

We have recently learned how to solve polynomial equations in Matlab, now we are going to visit a trick that will help you learn how to do Division and Multiplication of polynomial using Matlab.

Polynomial Division example


matlab-polynomial

Polynomial Multiplication example

matlab-polynomial

Matlab Polynomial

Multiplication of polynomial can be a very dreary task, so do division of polynomial. Matlab use the functions conv and deconv to help you do these tasks with the least commotion possible, and most importantly with the assurance to find the right result the quickest way possible.

Let get on some examples, those will help easily learn how to make use of conv (for multiplication) and deconv (for division).

Caution! We will not show you how to manually solve polynomial multiplication and polynomial division manually here. Matlab will help you do it, but it will not show you how to do it, so at this point we supposed you know how it is done. Check how to do it manually if you do not.

Example 1

matlab-polynomial

The code

s=[1 4];
t=[1 4 -3];
conv(s,t)

Which returns

matlab-polynomial

Rewritten, it gives the following

matlab-polynomial

Example 2

matlab-polynomial

The code

c=[1 0 4];
u=[1 3];
[p,r]=deconv(c,u)% r is the remainder of the division

Which returns

matlab-polynomial

Rewritten, it gives

matlab-polynomial

A bit of clarity

Top-down conversion. Here we simply need to indicate the coefficient and their position in the polynomial equation.

matlab-polynomial

Bottom-up conversion. Here we need to read Matlab outputs and rewrite it the way it is supposed to be, and it goes like this.

matlab-polynomial

Remember you need to put a zero, in case an order is not represented in the equation. See example below

matlab-polynomial

tchouken2

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