Creating and solving a polynomial equal to zero.

Hello Mathwork's community,

I'm trying to define as many polynomial functions as columns I have inside an inital matrix A, such as:

A = [-5000 1200 750 2000 1200; -200 150 60 40 50];

Since I have two columns, there'll be two functions that should look like:

Once the polynomial functions have been defiined, I'd like to solve x when the function equals to zero, so that the output for this two cases are:

OutPuts = [0.011369, 0.056055]

I hope I've explained my-self well enough, and that someone could please give me a hand.

Thank's in advance.

Santos

Answer 1

[Alan Stevens]

Something like this

A = [-5000 1200 750 2000 1200; -200 150 60 40 50];
A = fliplr(A);  % Do this in order to use the roots function

R1 = roots(A(1,:));  % roots of first row:  4 values from quartic polynomial
R2 = roots(A(2,:));  % roots of second row:          ditto

% R = 1./(1 + x)  so  x = 1/R - 1
x1 = 1./R1 - 1;
x2 = 1./R2 - 1;

x1(abs(imag(x1))>10^-8)=[]; % delete complex values 
x2(abs(imag(x2))>10^-8)=[]; % delete complex values 

disp(x1)
disp(x2)

[Santos García Rosado]

Thank you Alan! Simple and elegant!