MATLAB: Error ode must return column vector

code generationreturn 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?

Best Answer

Add the line
diffeq = zeros(4,1);
at the beginning of your function "ode".
Best wishes
Torsten.
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