May you guys help me I got stuck in developing a simple code... (solving diferential equations by using ode45)

1 次查看（过去 30 天）
Douglas Alves
Douglas Alves 2014-5-9
评论： Star Strider 2014-5-12
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;

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2014-5-9
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
  9 个评论
显示 7更早的评论

请先登录，再进行评论。

更多回答（1 个）

dpb
dpb 2014-5-9
...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 个评论
dpb
dpb 2014-5-9
编辑：dpb 2014-5-9
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...

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Programming 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by