The derivative function needs to have the input arguments specified. In your current code above, you have no inputs specified.
For the ode45 call, you need to pass a function handle that has only two inputs, the independent variable and the current state.
So your derivative function should look something like this:
function dTdz = Term_project2(z,T,p1,p2,q1,q2,U,Q,Cp1,Cp2L) % pass in all needed inputs
dTdz(1,1) = -(U*a)/(L*p1*Cp1*q1)*(T(1)-T(2))-Q/(p1*Cp1); % use T(1) and T(2) for T1 and T2
dTdz(2,1) = (U*a)/(L*p2*Cp2*q2)*(T(1)-T(2))-Q/(p2*Cp2);
end
And your calling code should look something like this:
U= 280;
a=2*.45*3.14159;
p1= 0.5;
L= 8000;
Cp1= 10;
Q=284;
p2= 1;
Cp2= 15;
q1= 0.5;
q2= 1;
zspan=[0:40];
T0= [12 5];
% 1st argument to ode45 below needs to be a function handle
% that takes z and T as inputs
[z,T]= ode45(@(z,T)Term_project2(z,T,p1,p2,q1,q2,U,Q,Cp1,Cp2L),zspan,T0);
plot(z,T(:,1),'-o',z,T(:,2),'-.')
