In slides Interp-243 and Interp-244, what does it mean for a pp to have continuous derivatives up to order -1, or a negative number in general? Thank you!
Continuity -1 means function is discontinuous.
Continuity 0 means function is continuous, but its derivatives may not be continuous.
For example, on page interp-241, the first plot is
of some C^{-1} linear pp.
The second plot is of some C^0 linear pp (or linear spline).
This clarifies, thank you:)