May you guys help me I got stuck in developing a simple code... (solving diferential equations by using ode45)
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Douglas Alves
le 9 Mai 2014
Commenté : Star Strider
le 12 Mai 2014
If I consider the function react2 and write the function react in the prompt command it will work!! But I want to use only the script window... Since when I'm using the prompt I first type "[t,y] = ode45('react2',[0 4],[1 0 0]);" and after that MATLAB calls the function react2 ... So I thought putting it all in a new window and executing it it would work since the first function is actually what I would've typed in the prompt... But it does not work! why?? how could I get the values for [t y] without having to type [t y ] = ode45('react2',[0 4],[1 0]) ?? HERE IS THE CODE thank you guys..
function react
[t,y] = ode45('react2',[0 4],[1 0 0]);
% =======================================
function dydx = react2(t,y)
dydx = zeros(size(y));
A = y(1); B = y(2); C = y(3);
k1 = 5 ; k2 = 2; k3 = 1;
% initial values (A0,B0,C0) = (1,0,0);
dydx(1) = -k1*A +k2*B ; dydx(2) = k1*A - (k2+k3)*B ;
dydx(3) = k3*B;
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Star Strider
le 9 Mai 2014
It works fine as an anonymous function:
react2 = @(t, y, k1, k2, k3) [(-k1.*y(1) + k2.*y(2)); (k1*y(1) - (k2+k3)*y(2)); k3.*y(2)];
k1 = 5 ; k2 = 2; k3 = 1;
[t,y] = ode45(@(t,y) react2(t, y, k1, k2, k3),[0 4],[1 0 0]);
figure(1)
plot(t, y)
legend('A', 'B', 'C', 'Location', 'NW')
grid
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dpb
le 9 Mai 2014
...I thought putting it all in a new window and executing it it would work...
I don't know what you mean by the above. If you create another m-file script react.m that contains just the command line
t,y] = ode45('react2',[0 4],[1 0 0]);
and execute
react
at the command window it will work.
You don't use the function keyword in scripts is perhaps your confusion.
Read up the doc's on programming scripts and functions to clarify the difference in depth.
2 commentaires
dpb
le 9 Mai 2014
Modifié(e) : dpb
le 9 Mai 2014
Need to see what you actually did, not just describe it.
ADDENDUM:
Went ahead and copied your function and created the script file--
>> type react.m
[t,y] = ode45('react2',[0 4],[1 0 0]);
>> react
>> plot(t,y)
>>
Seems to work just fine...at least a solution seems to have happened according to the plot...
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