I have a question about linear splines. A computer package I am using has the option to use linear splines, but there is no user manual I can find.
I am having problems with the kind of inputs the package wants.
The first input is a vector x with values sorted in ascending order with N+1 values. This is ok.
The second is a vector of zero order coefficients. This vector can be of length N or N+1. What I do not understand here is that it doesn't have to be of the same length as the x-vector, why is that?
The third is a vector with the slopes. This vector has to be of length N. Again why does it not have to be the same length as the x vector?
Here is a link to the documentation: link, the relevant info is in the first box under "Public constructors."
So what I am struggling with is that the vectors are of different length. If they were of the same length it would make better sense, because then it would be the x-value and the function value and the slope at each point. But with different lengths, what is is they are actually asking for?