MATLAB: Error

matrix

A = [ 0 0 0.43; 0.6 0 0; 0 0.75 0.96 ];

T = [ 1 2 3 4 5 10 20 25 50 75 ];

V0 = [ 42, 0, 95 ]';

V=zeros(3,length(T));

V(:,1)=V0;

i=0;

for t=T

      i=i+1;
      V(:,1)=(A^t)*V0;

end

figure

T=[0 1 2 3 4 5 10 20 25 50 75];

T2=log(T);

V2=log(V);

LINE 22 plot( T2, V2(1,:), 'b', T2, V2(2,:), 'g', T2, V2(3,:), 'r')

%legend('calves','yearlings','adults')

title('population versus time')

xlabel('time')

LINE 30 ylabel('population')

THAT ERROR WENT AWAY. NOW IT SAYS….

??? Error using ==> plot Vectors must be the same lengths.

Error in ==> project3 at 22 plot( T2, V2(1,:), 'b', T2, V2(2,:), 'g', T2, V2(3,:), 'r')

Best Answer

Which is line 48? Please show the traceback.

Image Analyst has proposed (A.^t)*V0 but I think you do want (A^t)*V0 . An array raised to a power is appropriate for a stocastic process. However, when you raise a 3 x 3 matrix to a power, you get out a 3 x 3 matrix. You then try to multiply that by a 1 x 3 matrix, which is going to be an error. I think your definition of V0 should not have the transpose at the end, and should just be

V0 = [ 42; 0; 95 ];

Related Solutions

MATLAB: I am trying to solve hindmarsh rose equation and i wrote the function for it.. But, as i plot the equation using ode45. i am getting error. I tried using ode15s but, it gives same error. Attached is the code along with the error.

Your error message says you have the line

[t,x] = ode15s(@(t,x) hindmarsh_rose, tspan, x0);

but the code you posted has the line

[t,x] = ode15s(@(t,x) hindmarsh_rose(x,u), tspan, x0); %using ode15

You did not post the code for the same version that you executed. The version that you posted, with the (x,u) would not produce the error message that you indicate.

However, line 1 of try1 establishes u as a row vector of length 501. Your code inside the hindmarsh_rose function includes the line

F = [Y-X.^3+3*X.^2-Z+u;1-5*X.^2-Y;0.001*(4*(X-(-1.618))-Z)]; %equations

The first component of that list, Y-X.^3+3*X.^2-Z+u, uses u and so would give a row vector of length 501 as its value. The second component of the list, 1-5*X.^2-Y, and the third component of the list, 0.001*(4*(X-(-1.618))-Z), do not use u, and so are going to give scalars. So your [] operation is going to try to do [1 x 501; 1 x 1; 1 x 1] which is going to fail because the number of columns is not the same for the ";" operation. If you were to code,

F = [Y-X.^3+3*X.^2-Z+u.';1-5*X.^2-Y;0.001*(4*(X-(-1.618))-Z)]; %equations

then that would give [501 x 1; 1 x 1; 1 x 1] which could succeed, giving a 503 x 1 output. However, that would then promptly fail because the number of values in the vector, 503, would not match the number of values in x0, namely 3.

My guess at what you want is

u =0:0.01:5; %range for u
x0 = [0.1,0.1,0.1]; %initial values
tspan = [0 25]; %time span
for K = 1 : length(u)
  [t,x] = ode15s(@(t,x) hindmarsh_rose(x,u(K)), tspan, x0); %using ode15
  plot(t,x);
  hold on
end

MATLAB: Error using plot Vectors must be the same lengths.

Maybe some previous result are interfering with your code, try this

clear
t=[0 .3 .5 .75 .95 .99];
for i = 1:length(t)
  A = [0.0 0.0 .42;.6 0.0 0.0;0.0 0.75 t(i)];
  [v,lambda] = eig(A);
  lambdavector = max(lambda);
  for y = 1:numel(lambdavector)
      if max(abs(lambda(:))) == abs(lambdavector(y))
          loc = y;
          deig = lambda(y,y);
      end
  end
  normv(:,i) = v(:,loc)/sum(v(:,loc));
end
c = normv(1,:);
y = normv(2,:);
a = normv(3,:);
figure
plot(t,abs(c),'b.-',t,abs(y),'g.-',t,abs(a),'r.-')
xlabel('Adult Survival Rate')
ylabel('Equilibrium Population')
title('Adult Survival Changed')
legend('Calves','Yearlings','Adults')

Some of your data are complex numbers, I replaced them by their modulus

You can also replace max(max(A)) by max(A(:))

Best Answer

Related Solutions

MATLAB: I am trying to solve hindmarsh rose equation and i wrote the function for it.. But, as i plot the equation using ode45. i am getting error. I tried using ode15s but, it gives same error. Attached is the code along with the error.

MATLAB: Error using plot Vectors must be the same lengths.

Related Question