how to enable the getdirectionalderivative function?

[mayongjie2]

Hi everyone,

My issue is I am willing to calculate the partial derivatives of outputs to the inputs, and to the internal states, of a fmu model exported from Openmodelica.
According to the documentation of fmi 2.0, the attribute 'providesDirectionalDerivatives' in fmu model, should be true, I think this should be set up during the fmu model exporting from the Openmodelica.
In model exchange mode, this attribute could be set as true when being exported from Openmodelica, however after I imported it into c program, I couldn't invoke the getdirectionalderivative function (or the cover function fmi2_import_get_directional_derivative) in fmi-library.
In co-simulation mode, this attribute couldn't even be changed, I tried adding '--providesDirectionalDerivatie=true' in the options-simulation tab, and in the commandline, both failed.

So how could I do, does fmi-library support this function getdirectionalderivative ?
Or is this because fmu from Openmodelica doesn't have this function ?

thanks a lot in advance !
My email: [email protected]

[filip-stenstrom]

FMI-Library does support it.

I don't know how OpenModelica works, but you can read the modelDescription.xml to find the value of providesDirectionalDerivatives for the specific FMU.

It's not clear what is failing for you (crash/incorrect outputs/...), but I would recommend that you make sure that the FMU instance is in a state where a call to fmi2GetDirectionalDerivative is allowed before calling.