# want to see where is the problem in this code doesn't give me result

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Kommentiert: Image Analyst am 11 Mär. 2023
function J = system_model_jacobian(x,y,z,k,a1,a2,b2,c,d,p,sigma,beta)
J = [p*(1-x/k)-a1*y, -a1*x+c*a1*y/(b2+y)-d, 0; a2*y*z/(b2+y)^2, c*a1*x*z/(b2+y)^2-d, -beta*z^2/(b2+y)+2*sigma*z; 0, 0, 0];
% Compute Jacobian matrix at the steady states
x1 = [0, 0, 0];
x2 = [k, 0, 0];
x3 = [d/(c*a1), p*b1/(c*k*a1^2), 0];
x4 = [(k*(sigma*p-a1*b2))/(p*sigma), p*b1/(c*k*a1^2), beta*(p*sigma*b1-c*a1^2*b2)/(a2*p*sigma^2)];
J1 = subs(J,{x,y,z},{x1(1),x1(2),x1(3)});
J2 = subs(J,{x,y,z},{x2(1),x2(2),x2(3)});
J3 = subs(J,{x,y,z},{x3(1),x3(2),x3(3)});
J4 = subs(J,{x,y,z},{x4(1),x4(2),x4(3)});
% Compute eigenvalues of each steady state
lambda1 = eig(J1);
lambda2 = eig(J2);
lambda3 = eig(J3);
lambda4 = eig(J4);
% Display results
disp(['Eigenvalues: ', num2str(lambda1(1)), ', ', num2str(lambda1(2)), ', ', num2str(lambda1(3))]);
disp(['Eigenvalues: ', num2str(lambda2(1)), ', ', num2str(lambda2(2)), ', ', num2str(lambda2(3))]);
disp(['Eigenvalues: ', num2str(lambda3(1)), ', ', num2str(lambda3(2)), ', ', num2str(lambda3(3))]);
disp(['Eigenvalues: ', num2str(lambda4(1)), ', ', num2str(lambda4(2)), ', ', num2str(lambda4(3))]);
end
##### 3 Kommentare2 ältere Kommentare anzeigen2 ältere Kommentare ausblenden
Rik am 10 Mär. 2023
This is perhaps related to the previous question, but that context might not be that helpful.

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### Antworten (1)

Image Analyst am 10 Mär. 2023
What did you pass in for x,y,z,k,a1,a2,b2,c,d,p,sigma,beta? You didn't just click the green run triangle, did you? Because doing that will not "invent" values to pass in for you.
What do you mean by "give me result"? Did you mean it doesn't give you any result at all? Or did you mean it gave you a result, but not the result you expected?
##### 6 Kommentare5 ältere Kommentare anzeigen5 ältere Kommentare ausblenden
Image Analyst am 11 Mär. 2023
You have to assign them to something, so your test script would be something like this
x = 1
y = 2
z = 3
k=42
a1=9
a2=5
b2=6
c=99
d=234234
p=4234
sigma=234
beta=0.5
J = system_model_jacobian(x,y,z,k,a1,a2,b2,c,d,p,sigma,beta)

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