Interaction between categorical and spline predictor?

[olafdimigen]

Do we have any experience with that? Produces error:

Error using classreg.regr.FormulaProcessor>parseStr (line 663)
Unable to understand the character vector 'response ~1+cat(myfactor)*spl(mysplinepredictor,5)+mylinearcovariate'.

[behinger]

interactions with splines are currently not supported

Edit: One would need to specify the interaction manually:
for e = 1:length(EEG.event)
EEG.event(e).mysplinepredictor_factorA = EEG.event(e).mysplinepredictor.*double(EEG.event(e).myfactor=='FactorLevelA');
EEG.event(e).mysplinepredictor_factorB = EEG.event(e).mysplinepredictor.*double(EEG.event(e).myfactor=='FactorLevelB');

And then add the spline twice
spl(mysplinepredictor_factorA,5) + spl(mysplinepredictor_factorB,5)