statespace solver: A & B matrix must be functions (of t)

[JBlackhole]

To all,

Made some minor progress in understanding & using the statespace solver.

As my test case is a 2-dofs system I think I have established the matrices required by the solver.

However the solver needs/wants the A & B matrices to be functions (of time in my case) but cannot set it up correctly (see attached). I did find an old thread on a similar issue but cannot open the file

Any suggestion on the correct syntax?

Thanks

Regards

[-MFra-]

Hi JB,

But A (t) does not seem to be correctly defined. You should correct it:

[JBlackhole]

thanks

[AlanStevens · Accepted solution]

u(t)  must be a 2x1 vector.

A(t) has C and K the wrong way round.

See attached for corrections.

Alan

[JBlackhole]

Thanks

u(t): forgot about that

not sure I understand the K and C being inverted in the A matrix as it seems to correspond to the notes

[-MFra-]

The Shannon sampling theorem says that the sampling frequency of a time signal, must be equal to or greater than two times the frequency band of the given signal.

Moreover something is wrong with the index i:

[JBlackhole]

not sure why I cannot convert the predicted solution (using the ODE) inot a sampled vector to be used in the FFT

look like MC doesn't like starting the sampling at i=0. Starting at 1 seems to be OK eventough I get a flat FFT!