[Rd] Suggest adding a 'pivot' argument to qr.R
pdalgd at gmail.com
Fri Sep 7 20:42:31 CEST 2012
On Sep 7, 2012, at 17:16 , Tim Hesterberg wrote:
> I suggest adding a 'pivot' argument to qr.R, to obtain columns in the
> same order as the original x, so that
> a <- qr(x)
> qr.Q(a) %*% qr.R(a, pivot=TRUE)
> returns x.
That would come spiraling down in flames the first time someone tried to use backsolve on it, wouldn't it? I mean, a major point of QR is that R is triangular; doesn't make much sense to permute the columns without retaining the pivoting permutation.
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
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