[Numpy-discussion] LU factorization?

Charles R Harris charlesr.harris@gmail....
Wed Oct 15 15:33:47 CDT 2008


On Wed, Oct 15, 2008 at 2:26 PM, Robert Kern <robert.kern@gmail.com> wrote:

> On Wed, Oct 15, 2008 at 15:21, Charles R Harris
> <charlesr.harris@gmail.com> wrote:
> >
> > On Wed, Oct 15, 2008 at 2:04 PM, Robert Kern <robert.kern@gmail.com>
> wrote:
> >>
> >> On Wed, Oct 15, 2008 at 14:49, Charles R Harris
> >> <charlesr.harris@gmail.com> wrote:
> >> >
> >> > On Wed, Oct 15, 2008 at 1:06 PM, Robert Kern <robert.kern@gmail.com>
> >> > wrote:
> >> >>
> >> >> On Wed, Oct 15, 2008 at 00:23, Charles R Harris
> >> >> <charlesr.harris@gmail.com> wrote:
> >> >> > Hi All,
> >> >> >
> >> >> > numpy.linalg has qr and cholesky factorizations, but LU
> factorization
> >> >> > is
> >> >> > only available in scipy. That doesn't seem quite right. I think is
> >> >> > would
> >> >> > make sense to include the LU factorization in numpy among the basic
> >> >> > linalg
> >> >> > operations, and probably LU_solve also. Thoughts?
> >> >>
> >> >> -1. As far as I am concerned, numpy.linalg exists because Numeric had
> >> >> LinearAlgebra, and we had to provide it to allow people to upgrade. I
> >> >> do not want to see an expansion of functionality to maintain.
> >> >
> >> > I would be happier with that argument if scipy was broken into
> >> > separately
> >> > downloadable modules and released on a regular schedule.
> >>
> >> Then that is the deficiency that we should spend time on, not
> >> duplicating the functionality again.
> >
> > Should we break out the linear algebra part of scipy and make it a
> separate
> > package? I suspect that would add to the build burden, because we would
> then
> > have a new package to maintain and release binaries for. I don't see the
> > problem with having a bit of linear algebra as part of the numpy base
> > package.
>
> Which bits? The current set has worked fine for more than 10 years.
> Where do we stop? There will always be someone who wants just one more
> function. And a case can always be made that adding just that function
> is reasonable.
>

I would just add the bits that are already there and don't add any extra
dependencies, i.e., they are there when numpy is built without ATLAS or
other external packages. The determinant function in linalg uses the LU
decomposition, so I don't see why that shouldn't be available to the general
user.

Chuck
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