Solve first ode using ode45

Hello, my question is i have first ode dT/dt = -0.0004*[T(t) - 5], may i know how to use ode45 to solve t in the range T [8 88]? Can i know how about the script? Thank you for your help.

Answer 1

[Walter Roberson]

format long g
syms T(t) T8
dTdt = diff(T(t),t)

dTdt = 

eqn = dTdt == -0.0004*(T - 5)

eqn(t) = 

init = T(8) == T8

init = 

sol = simplify(dsolve([eqn, init]))

sol = 

Specific_T8 = 6

Specific_T8 = 
     6

Tsol = subs(sol, T8, Specific_T8)

Tsol = 

fplot(Tsol, [8 88])

[Lim Xiao Hui]

thank you

Answer 2

[Jan]

You can modify the examples of the documentation easily, see: doc ode45

Temperature0       = 6.2;  % Your initial value
[Time, Temperatur] = ode45(@fcn, [8, 88], Temperature0)
plot(Time, Temperature);

function dT = fcn(Time, Temperature)
dT = -0.0004 * (Temperatur - 5);
end

[Lim Xiao Hui]

thank you