Calculating the differences matrix 'L' of order 'm', depending on the number of knots 'k'.
Environment of pendensity()
Returns the difference matrix of order 'm' for given number of knots 'K'.
The needed values are saved in the environment.
Right now, the difference matrix is implemented for m=1,2,3,4.
Christian Schellhase <firstname.lastname@example.org>
Density Estimation with a Penalized Mixture Approach, Schellhase C. and Kauermann G. (2012), Computational Statistics 27 (4), p. 757-777.