Problem with "roots" command

Hello

In the following code, the "roots" command should give us 3*6 matrix with 18 values, because A and B have 6 values and the equation is 3rd order. But a 3*1 matrix with 3 values have been obtained. It seems that only one step has passed. What is the problem?

clc
clear
close all

k1 = 0.841;
k2 = 0.537;
k3 = 0.942;
k4 = 0.019;
k5 = 0.720;

T = 333.15:10:383.15;    % K
P = 2e7:0.2e7:3e7;    % Pa
Tc = 304.12;    % K
Pc = 73.74e5;    % Pa
Vc = 9.407e-5;    % m^3/mol
Zc = 0.274;
w = 0.225;
R = 8.314;    % m^3*Pa/mol*K
Mw = 44.01;    % g/mol

Tr = T/Tc;
Pr = P/Pc;

m1 = 0.2513+(0.4178*w)-(0.0207*w^2);
m2 = -0.1382-(0.5923*w)-(1.0493*w^2);
m3 = 0.1931+(1.3955*w)+(0.1961*w^2);
alpha = 1+(m1*(1-Tr))+(m2*(1-Tr).^2)+(m3*(1-Tr).^3);

n = 0.2155-(0.9069*w)-(0.206*w^2);
beta = 1+(n*(1-Tr));

a = 0.47448*(((R*Tc)^2)/Pc)*alpha;
b = 0.06824*((R*Tc)/Pc)*beta;

zarib = (k1+k2*log(Tr)+k3*log(Pr))./(1+k4*log(Tr).^2+k5*log(Pr).^2);

A = zarib.*(a.*P)./((R.*T).^2);
B = (b.*P)./(R.*T);

for u = 1:6   
    Root = roots([1 ...
                 (-1)...
                 (A(u)-B(u).^2-2*B(u))...
                 (-A(u).*B(u)-B(u).^2)]);
    zmax = 0;
    zmin = 1;
    for r = 1:3  
        if imag(Root(r)) == 0
            if Root(r) > 0  &&  Root(r) > zmax  &&  Root(r) < 1
                zmax(u) = Root(r);
            end
            if Root(r) > 0  &&  Root(r) < zmin
                zmin(u) = Root(r);
            end            
        end
    end
end

vm = (zmax.*R.*T)./(P);    % m^3/mol    

ro = (0.001)^2*(Mw./vm);    % g/cm^3

Answer 1

[OCDER]

Root = roots(...) %Not saving output correctly here

This will override the value of Root every iteration, resulting in a 3x1 matrix. To save the results of each iteration, you need to change where the data is saved to in Root.

Root = zeros(3, 6);
for u = 1:6
  Root(:, u) = roots(...);
end

[OCDER]

Replace " Root(r) " with " Root(r, u) "