>> other solvers): at line 336, it should be
>> 
>> vdelta = abs(y5 - y4);

> So number of evaluations and steps increased dramatically. I can see the same 
> for ode45..ode78. Can you send an example where I can see results becoming 
> better if I use your modification?

vdelta is an error estimate (in fact, it is compared few lines below with 
the tolerance)

if (all (vdelta <= vtau))

What happens if it is negative? Or, even worse, complex? Of course, 
without the absolute value you have less time steps, only because the 
comparison with the tolerance is a non-sense.

Moreover, if you try to solve y'=sqrt(-1)*y you get the complex conjugate 
solution. In fact, the conjugate-transpose symbol ' is erroneously 
used instead of only-transpose .'

I think I will have some time to further investigate the codes (at least, 
the m-files).

Best regards,

Marco

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