[R] Solving Matrices

etb lizzy at noradd.org
Thu Apr 15 18:05:21 CEST 2004

James writes:

> Have you tried det(x) and/or eigen(x) ?
> A zero determinant (within computer precision) means that the matrix
> does not have full rank, i.e. it does not span R4.  Count how many
> eigenvalues are zero (within computer precision).  What does this
> tell you?

I'm still on chapter 1 and we have not yet covered eigenvalues so this
is a bit fuzzy.

> >    In the Solutions Manual, there is mention of the gauss() and
> >bgauss() functions which apparently written by Lay - these are to
> >speed up matrix reduction but I have not noticed these functions in R.
> Have you encountered speed problems in R?  Do you really need these
> functions in R in addition to solve(), backsolve() etc. ?  If you
> just want to learn about how they work you could have a look at the
> Matlab code for these functions (which I think you have access to).
> You could even try rewriting them in R yourself.

No, the speed is fine but I'm in early Linear Algebra and am working
with basic matrices right now. I do have access to the author's
functions and I may try re-writing those in R - that should be a good
project and should help me better understand R as I'm a novice.

Thank you,

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