Hey Meredith,
Try to define the initial condition (h0), time interval between which you are trying to solve the ODE (tspan) first. For example,
tspan = [0,5]
h0 = 0
Then, call the ode45 function as shown below,
[t,h] = ode45(@odefun, tspan, h0)
Now, we need to define the 'odefun'. Since you require it to be h'= T(h) x h, define it as follows:
function dhdt = odefun(t,h)
dhdt = T(h) * h % You should define T(h) as well
end
Regards, Zenin