WHY do I get this error

Question

mahesh tom 2017-11-17

2
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/367609-why-do-i-get-this-error

评论： asavra siddiqui 2021-4-10

采纳的回答： Mischa Kim

function dydt = free25(t,y);

g = 9.81;

l = 1;

dydt = [y(2);-g/l.*sin(y(1))];

end

[t,y]= ode45('free25',[0 10],[0 0.09]);%I typed this in command window

plot(t,y(:,1));

refline([0 0]);

Error using feval Undefined function 'free25' for input arguments of type 'double'.

Error in odearguments (line 87) 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);

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Answer 1

Mischa Kim 2017-11-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/367609-why-do-i-get-this-error#answer_291709

编辑：Mischa Kim 2017-11-17

mahesh, is the above code all in one and the same script? If it is modify like this:

 [t,y]= ode45(@free25,[0 10],[0 0.09]);%I typed this in command window
 plot(t,y(:,1))
 function dydt = free25(t,y)
 g = 9.81;
 l = 1;
 dydt = [y(2);-g/l.*sin(y(1))];
 end

Another option would be to store the first part of the script (first two commands) in one function and the second part in a different function. For this second option make sure you name the file the same way you name the function: free25.m