error in ode45 - must return a column vector

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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 91) THERMAL_BUBBLE must return a column vector.

Error in ode45 (line 114) [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

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

function  dy=thermal_bubble(t,y)
dy=zeros(1,2,3);
d=998;
c=1500;
r0=10^-5; 
s=0.0725; 
e=3/4; 
k=0.016;
u=0.000001; 
p0=10^5;
f=25000; 
pa=1000; 
cv=1.5*10^3; 
a=2.338*10^-5; 
Tinf=300;
g=1.31;  
dy(1)=y(2);
dy(2)=((1/d)*(1+(y(2))/c)*(p0+2*s/r0)*(((y(1))/r0)^(3*e))+((p0+2*s/r0)*(((y(1))/r0)^(3*e))*g*((-3*y(2))/y(1))+(g-1)*((3*k/y(1))*(y(3)-Tinf)*sqrt(3*y(2)*(g-1)/(a*y(1))))-4*u*(((y(2))/(y(1)))^2)+2*s*y(2)/((y(1))^2)+2*pi*f*pa*cos(2*pi*f*t))*((y(1))/(d*c))-(3/2)*((y(2))^2)*(1-(y(2))/c))*(((y(1))*(1-(y(2))/c))^-1)+(1+(4*u/(d*c))*(y(1)*((1-(y(2))/c))^-1))^-1;                                              
dy(3)=((4*pi*(y(1))^2)/((cv*4*pi*r0^3)/3))*(k*sqrt(abs(y(2))/(a*y(1))))*(y(3)-Tinf)-y(2)*(p0+2*s/r0)*((y(1))/r0)^(3*e);
    end

---------------------------------------------------------------------------------------------------------------------------------------------- and then i run this in command window and error appears

>>[t,y]=ode45(@thermal_bubble,[0 20/25000],[0.00001 0 25]);