Return the variance-covariance matrix for the specified submodel.
# S3 method for lmSubsets
vcov(object, size, best = 1, ...)# S3 method for lmSelect
vcov(object, best = 1, ...)
"lmSubsets", "lmSelect"---a subset
regression
integer---the submodel size
integer---the submodel position
ignored
double[,]---the variance-covariance matrix
lmSubsets() for all-subsets
regression
lmSelect() for best-subset
regression
vcov() for the S3 generic