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())
dot(u, v)
Arguments
A
a formula. In mat and singvals,
only the right-hand side is used.
u
a numeric vector
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.
v
a numeric vector
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)
dot(b,c) # dot product# Formula interfacemat(~a+b)
mat(~a+b+1)
mat(~length+sex, data=KidsFeet)
singvals(~length*sex*width, data=KidsFeet)