MATLAB: ERROR: odearguments (line 90), ode45 (line 113)

Question

function yprime=swing_brake(t,y)

cd=0.6;

A0=0.5*10^(-6);

density=800;

Bulk=2*10^9;

Ap=10^(-4);

M=0.1;

k=40000;

x0=0.005;

V10=10^(-4);

V20=10^(-5);

Amax=0.5*10^(-6);

delP_set=100*10^5;

x=delP_set-y(2);

if (x <= 50)

Ared=Amax;

else

Ared=-Amax/(50-y(2))*(x-50)+Amax;

DelP=y(1)-y(2);

Q2=cd*A0*sqrt(2*y(2)/density);

Qred=cd*Ared*sqrt(2*abs(DelP)/density);

yprime(1)=Bulk*(Ap*y(4)-Qred)/(V10-Ap*y(3));

yprime(2)=Bulk*(Qred-Q2)/V20;

yprime(3)=y(4);

yprime(4)=(k*(x0-y(3))+y(1)*Ap)/M;

end

>>[t,y]=ode45('swing_brake',[0 0.06],[0 0 0 0]);

ERROR:

odearguments (line 90)

SWING_BRAKE must return a column vector.

ode45 (line 113)

[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, …

Answer 1

add:

yprime = zeros(4,1);

before assigning values to yprime