Hi everyone im trying to solve a system of coupled ordinary differential equations using ODE45 and i keep getting this error: Error using odearguments (line 90) GSM_N must return a column vector. Error in ode23 (line 112) [neq, tspan, ntspan, next,

i put my code below for you guys to help me find my error thanks

function dy = gsm_n(t,y)
    global D l rho k1 n1  nn Mn Jm Ui Ra Re La Oh a b p x

      m= rho*pi*((D*D)/4)*l; %Berechnung der Masse

      Jg= 0.5*m*((D*D)/4); %Berechnung der Massenträgheitsmoment der GSM

      phi= Ui./(k1*n1); %Berechnung der Fluss

     dy1 = ((((n1-y(1))/(n1-nn))*Mn)-((k1*phi*y(2))/(2*pi)))/(2*pi*(Jg+Jm)); %mit y(1)= dndt

      PHI= -a*cos(x)+b*(2*x-20); 

      We= 952*p; %gesamterregerwindungszahl

     dy2= ((k1*phi*y(1))-((Ra+Re)*y(2)))./(La+((1+Oh)*We*PHI)); %mit y(2)= dIedt

     dy = [dy1;dy2];

and then i run this in a main like this:

global D p l rho k1 n1 Ra Re La x Oh a b nn Mn Jm Ui %definition von global Variable

D= 0.158;
p=2;
l=0.25;
rho=2700;
k1= 720;
n1=50;
Ra= 0.198;
Re= 115;
La= 0.0042;
Oh=0.1;
a= -0.01792;
b= 0.0002088;
x= (0:0.07:1.3);
nn= 48.8167;
Mn= 24;
Jm= 0.024;
Ui=[4.8 105 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440];

t = [0 10];
Y0= [50 0];
[T,Y] = ode23(@gsm_n, t, Y0);

plot(T,Y(:,1),'r',T,Y(:,2),'b');

Answer 1

[Torsten]

dy1 and dy2 should both be scalar values.

In your case, they are not since phi is a vector.

Best wishes

Torsten.

Answer 2

[kamdam Sophia]

thx @Torsten.