Error ode must return column vector

function diffeq = ode(w, v)

k1 = 0.5*exp(2-640/v(4));

Kc = 10*exp(2064/v(4)-7.2);

k3 = 0.005*exp(4.6-2116/v(4));

Ta = 500;
Ua_rho = 16;
Cpa =100;
Cpb =100;
Cpc =100;
deltaH1=-1800;

FC = v(1)*Cpa +v(2)*Cpb + v(3)*Cpc;

diffeq(1)=k1*v(2)-k1/Kc*v(1);

diffeq(2)=k1/Kc*v(1)-v(2)*(k1+k3);

diffeq(3)=k3*v(2);

diffeq(4)=((k1/Kc*v(1)-v(2)*(k1+k3))*deltaH1 - Ua_rho*(v(4)-Ta))/FC;

====

wspan = [0 100];

IC(1)=1; IC(2)=1; IC(3)=0; IC(4)=330;
[w,vv] = ode15s(@ode,wspan,IC);

Fa = vv(:,1); Fb = vv(:,2); Fc = vv(:,3); T = vv(:,4);

plot(w,Fa, w,Fb, w,Fc, w,T)
xlabel('weight of catalyst')
ylabel('Flow Rates and Temp')

Error using odearguments (line 93)
ODE must return a column vector.

Error in ode15s (line 150)
    odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

Error in odesolve (line 5)
[w,vv] = ode15s(@ode,wspan,IC);

It says my ode needs to return a column, but my ode if im not mistaken is a 4by4 matrix so I don't understand how is it no a column vector?

Answer 1

[Torsten]

Add the line

diffeq = zeros(4,1);

at the beginning of your function "ode".

Best wishes

Torsten.

Answer 2

[Walter Roberson]

A column vector has to be something-by-1 . A 4 x 4 is not a vector. You need to return 16 x 1.