These basis function can model interaction between two or more variables.
While it rises, the basis function of the previous control point falls.
The basis function is no longer differentiable at that point.
The set of basis functions is usually called a dictionary.
To solve the second problem, one way is to design special basis functions.
This is not the case for other radial basis functions.
However, the issue that these basis functions may be different from those in which the risk decisions were expressed is not widely appreciated.
Then the basis functions which have no t in them generate .
There are various methods of creating the basis functions for the least squares fit.
A separate consideration is the smoothness of the basis functions.