Solving 2 ODE's with ode45

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Tarek Chahattou
Tarek Chahattou 2019-10-23
回答： Stephan 2019-10-23
New Doc 2019-10-22 22.24.58_1.jpg
Im trying to solve these 2 differential equations like this:
tfinal = 100;
t = linspace(0,tfinal,100);
winitial = [1 300];
[T, Ca] = ode45(@sub1,t,winitial)
plot(t,Ca)
%%%%%%%%% Subfunction
function d_dt = sub1(Ca,T)
d_dt = zeros(2, 1);
d_dt(1,1) = -0.1*Ca*exp(-300/T);
d_dt(2,1) = 1*Ca*exp(-300/T);
end
but i keep getting these errors. Does it have something to do with the subfunction? I was having trouble with it
Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-2.
Error in explicit_Eu_hw>sub1 (line 28)
d_dt(1,1) = -0.1*Ca*exp(-300/T);
Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.
Error in ode45 (line 115)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);
Error in explicit_Eu_hw (line 20)
[T, Ca] = ode45(@sub1,t,winitial)

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采纳的回答

Stephan
Stephan 2019-10-23
tfinal = 100;
tspan = [0 tfinal];
winitial = [1 300];
[t,y] = ode45(@sub1,tspan,winitial)
plot(t,y,'LineWidth',2)
%%%%%%%%%Subfunction
function d_dt = sub1(t,y)
Ca = y(1);
T=y(2);
d_dt = zeros(2, 1);
d_dt(1,1) = -0.1*Ca*exp(-300/T);
d_dt(2,1) = 1*Ca*exp(-300/T);
end

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