# Finding Polynomials From Their Known Roots In Matlab(Illustrated Expression)

We explained the finding roots of a polynomial in Matlab **in here**. Also you can do same thing in reverse direction. You can find polynomes from their roots in Matlab with ‘poly()’ command. In here, we explained how to find specific polynomial from its known roots with ‘poly()’ command in Matlab, with a very basic example.

### How To Use ‘poly()’ Command In Matlab?

Finding polynomes from their known roots in Matlab with poly() command.

To find polynomial from its known roots in Matlab, you need to define all the roots in a vector. For example we defined 4 roots of a polynomial in vector ‘a’ above. What we did is, we typed the polynomial ‘a’ into the poly() command, then assigned it to a variable ‘b’. As you see above again, the result is shown with green arrow. This vector ‘b’ represents the unknown polynomial that calculated from its roots.

Also you can directly type all the roots inside the pharanthesis of poly() command in Matlab, as shown by green box above.

The logic of these results that represents polynomials, all the elements respresents the coefficients of polynomial that has one variable. For example result ‘b’ represents the polynomial of x^4-4x^3+6x^2-4x^. All the coefficients are represented by an element in vector ‘b’ and ‘d’, from left to right.

Finding out unknown polynomial from its known roots is very easy like above with ‘poly()’ command in Matlab. Do not forget to leave your comments and questions about ‘poly()’ command in Matlab to find polynomials from its roots below. You feedback is very important for us.