linear.algebra: Functions for teaching linear algebra.
Description
These functions provide a formula based interface to the construction
of matrices from data and for fitting. You can use them both for numerical vectors
and for functions of variables in data frames.
These functions are intended to support teaching basic linear algebra
with a particular connection to statistics.
Usage
mat(A, data = parent.frame())
singvals(A, data = parent.frame())
Arguments
A
a formula. In mat and singvals,
only the right-hand side is used.
data
a data frame from which to pull out numerical values
for the variables in the formula
...
additional arguments (currently ignored)
mat returns a model matrix
To demonstrate singularity, use singvals.
Value
mat returns a matrix
singvals gives singular values for each column in the model matrix
a <- c(1,0,0); b <- c(1,2,3); c <- c(4,5,6); x <- rnorm(3)
# Formula interfacemat(~a+b)
mat(~a+b+1)
mat(~length+sex, data=KidsFeet)
singvals(~length*sex*width, data=KidsFeet)