On Thu, Mar 7, 2013 at 5:01 PM, Ether Jones <maxima at etherjones.us> wrote:
> Does Maxima have QR factorization built in?
>
> i.e. A = Q*R
>
> where A has more rows than columns, Q is orthogonal, and R is upper
> triangular?
>
>
If you want a numerical solution, it looks like maxima has the Lapack
routine dgeqrf for real matrices. Use "? dgeqrf" to see how to use it.
> Also, does Maxima have a backsubstitution method, so that
> the overdetermined linear system Ax~b can be solved using QR
> factorization by solving Rx=Q'b by backsubstitution?
>
It looks like dgetrs is the lapack routine to do this. It seems not
supported by maxima, but it shouldn't be too hard to add that.
Ray
>
>
>
>
> _______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima
>
>