Hi, in the constructors documentation, one can read
It should be “default” instead of “defult” 
I just change all the “defult” into “default” in the root code (there was more that the ones you saw). Thanks.
I saw your modification. I think you forgot the ones I mention because you did not edit anby file related to ROOT::Math::Interpolator 
You are right I missed those because they are in some kind of unusual place in the source tree.
I fixed it now (plus some others you did not mentioned 
)
Thanks