laplacian {mda} | R Documentation |
Creates a penalty matrix for use by gen.ridge
for
two-dimensional smoothing.
laplacian(size, compose) laplacian(size = 16, compose = FALSE)
size |
dimension of the image is |
compose |
default is |
Formulas are used to construct a laplacian for smoothing a square image.
If compose=FALSE
, an eigen-decomposition object is
returned. The vectors
component is a size^2 x size^2
orthogonal matrix, and the $values
component is a size^2
vector of non-negative eigen-values. If compose=TRUE
, these are
multiplied together to form a single matrix.
Trevor Hastie <hastie@stanford.edu
Here we follow very closely the material on page 635 in JASA 1991 of O'Sullivan's article on discretized Laplacian Smoothing