[Octave-bug-tracker] [bug #60748] lsode throws an unexpected and ill-founded error

[Kai Torben Ohlhus]

Update of bug #60748 (project octave):

                Priority:              5 - Normal => 3 - Low                
              Item Group: Unexpected Error or Warning => Documentation        
 
                  Status:                    None => Invalid                
             Open/Closed:                    Open => Closed                 
        Operating System:       Microsoft Windows => Any                    

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Follow-up Comment #2:

Thanks for reporting this issue.

In your example, you are working with row instead of column vectors (see the
example in the manual
https://octave.org/doc/v6.2.0/Ordinary-Differential-Equations.html).

Your example rewritten:


x0=[1;0];
f=@(x,t) [-x(2);x(1)];%some vector function
slnf=lsode(f,x0,[0,pi]);%correct

g=@(x,t) circshift(x,1).*linspace(-1,1,length(x))';%strange but
xr=rand(2,1);
assert(g(xr)==f(xr)); %they are perfectly equal in 2D

slng=lsode(g,x0,[0,pi]); %no error


Regarding a better documentation of lsode, there is already bug #57508. 
Please contribute a nice ODE example there, that would have helped you and I
can add it to the manual 🙂

If there are any further issues, we can reopen this bug report.


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