ode45 - return a column vector
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Below is the function i have described:
function ssir = fnsir(t,y)
b = 0.1;
q = 0.022;
m = 0.012;
l = 0.125;
r = 0.14;
ssir(1) = q - m*y(1)-b*y(1)*y(2)+ l*y(3);
ssir(2) = (b*y(1)*y(2))-((m+r)*y(2));
ssir(3) = (r*y(2)) - (y(3)*(m+r));
------------------------------
And i am calling this function using:
[t,y]=ode45('fnsir', [0 10], [200 20 2])
and i am getting the following error:
??? Error using ==> odearguments at 113 FNSIR must return a column vector.
Error in ==> ode45 at 173 [neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...
--------------------------
can anyone please help me sort this out
Thanks!
3 个评论
SAFA BOUDHRAA
2018-1-7
I'am having the same problem, but the solution mentioned doesn't help
Walter Roberson
2018-1-7
SAFA BOUDHRAA: As the very last step of your function, turn the output into a column vector. For example if you currently have
function dy = MyOde(....)
...
dy = ....
then after that do
dy = dy(:);
as the last thing before returning. The variable you should do this to is the one returned by your function.
If that does not work, then use the debugger to check whether possibly you are returning the empty vector.
Walter Roberson
2019-11-30
Hoda Khesali Aghtaei comments to me:
was helpful
采纳的回答
ODE45 expects the reply as [3 x 1] vector, but your code creates a [1 x 3] vector. Two solutions:
1. Pre-allocate ssir as a vector of the wanted shape:
ssir = zeros(3, 1);
ssir(1) = ...
2. Or append a reshaping as last line of the function fnsir:
ssir = ssir(:);
As you see, the error message is rather clear. It is worth to read Matlab's messages carefully. They are the best messages I've ever seen in a commercial software.
8 个评论
Ojaswita
2013-5-14
Jan
2013-5-14
Your questions are welcome in the forum. And I know, that one can desperate on such tiny details. Therefore I spend time in this forum to answer and I'm very happy about the time, TMW has spent to create the helpful error messages - compared to the confusing stuff show by e.g. Microsoft programs...
Ojaswita
2013-9-24
Frank Böhnke
2016-12-19
thanks very much, that answer helped on the 19 th Dec 2016 Frank, Munich
SY
2017-10-30
Wow, I've been trying to fix this exact problem for my program and this answer from four years ago really helped me. Thanks!
Kalpit Bakal
2019-3-21
Thank you so much for the answer. My code work perfectly after this. Best part about peer to peer learning!
Ali Amirfaridi
2020-4-28
编辑：Ali Amirfaridi
2021-4-30
still helping in 2020! thank you mate
Yashee Sinha
2021-4-27
thanks a lot!
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