Matlab (Embedded) Function Block sample time

Hey

I have a model that uses a variable step solver (ODE45). How do I ensure that the Matlab function blocks in my model are executed only once during each sample time, i.e. at the same sample time as the rest of my model considering that the sample time can vary with a variable step solver.

I know it is quite easy to do this with a fixed step solver. However my model requires a very small sample time (<0.01) to run with a fixed step solver (such as ODE4) to avoid singularities. Due to complexity of the matlab function block calculations performed, this is very very slow.

Appreciate any thoughts and advice to solve this problem!

Thanks in advance,

Emmanuel

Answer 1

[Azzi Abdelmalek]

That depends on your embedded function inputs, if they came from a block with sample time, then set those sample time to inherited. If you can not, then pass those input through a zoh block with sample time set to inherited

[Emmanuel]

should I set the sample time of the embedded matlab function blocks to inherited? If I do this then it seems to run multiple times each time step (during some time steps).

This is because I ask it to display some results in the command window and it seems to display the same results multiple times (during some time steps only!)

is there a way to 'tell' the embedded matlab block to 'grab' the current sample time from the rest of the simulation?

[Abid Rahman Kodakkadan]

Is there any answer on this? I also experience this and the embedded function is taking in absurd values that a scope in simulink cannot detect. I also guess this is because the function executes multiple times during one simulation step.