ode45 too many input arguments
显示 更早的评论
Hi. This is the code i've been working on, to find values of a column vector concentration c, that varies with time t, as a chemical reaction happens, which basically means solving three rate equations simultaneously.
The error is given below.
The code is given below here.
clear
global k1 k2 %rate constants
k1=2; k2=1; ca0=2; tfin=(1/3);
C0(1)=ca0;C0(2)=0;C0(3)=0; %initial condition of c
timspan=[0,tfin];
[t,C]=ode45(@exampleode,timspan,C0);
%function to calculate rate of change of elements in "c"
function dc_dt=exampleode(C)
global k1 k2
dc_dt(1)=-k1*C(1)-k2*C(1)*C(1);
dc_dt(2)=k1*C(1);
dc_dt(3)=k2*C(1)^2;
end
采纳的回答
Cris LaPierre
2021-3-13
编辑：Cris LaPierre
2021-3-13
The first input to your odefun needs to be t.
Also note that the output of your odefun needs to be a column vector.
Final comment is to not use global variables. Here I use nested functions, but you can also see this example for a way to pass them in the function declaration.
function Ct()
k1=2; k2=1; ca0=2; tfin=(1/3);
C0(1)=ca0;C0(2)=0;C0(3)=0; %initial condition of c
timspan=[0,tfin];
[t,C]=ode45(@exampleode,timspan,C0);
%function to calculate rate of change of elements in "c"
function dc_dt=exampleode(t,C)
dc_dt(1,1)=-k1*C(1)-k2*C(1)*C(1);
dc_dt(2,1)=k1*C(1);
dc_dt(3,1)=k2*C(1)^2;
end
end
更多回答（1 个）
Walter Roberson
2021-3-13
1 个投票
The ode function always gets passed time and boundary conditions. It is not required to pay attention to either, but it must be prepared to receive them. You can create a function that does not pass through t but does pass through k1, k2 so that you can get rid of the globals:
类别
在 帮助中心 和 File Exchange 中查找有关 Ordinary Differential Equations 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
