Continuation of Work on Projects
Start a design document
for your project.
At this stage we want as complete and precise a description of the problem or problems the package will solve. A high-level description of the problem is just fine at this point, but it must be precise.
Suppose you were going to write a package having a function to do
least squares regression, like what the R function lm
does but dumber. Given a vector y (the response
)
and a matrix M (the design
or model
) we
will find a β that minimizes the quantity
(y − M β)T
(y − M β)
We will do this by solving the normal equations
MT y
=
MT M β
And we will do that by using a QR decomposition of the model matrix M = Q R where Q is orthogonal and R is upper triangular.
And so forth. Stuff at this level of generality, but very precise.
