degrees of freedom, i.e., number of random regressors
rdist
random distribution function for sampling
args
arguments for rdist
nrow
number of rows in resulting matrix. This can often be omitted in
the context of functions like lm where it is inferred from the data frame,
if one is provided.
seed
seed for random number generation
Value
A matrix of random variates with df columns.
In its intended use, the number of rows will be selected to match the
size of the data frame supplied to lm