[R] left.solve

[Martin Maechler]

>>>>> "SRL" == Stephen R Laniel <laniel at stat.cmu.edu> writes:

    SRL> I have sort of an emergency question for the list.  One of my
    SRL> professors for an S-Plus intensive class distributed a function to
    SRL> produce partial regression plots.  I need to run it under R,
    SRL> because I'm doing the homework on my home computer with a modem;
    SRL> hence I don't have the speed required to emulate X-Windows and run
    SRL> S Plus off one of the campus servers.  Bottom line: I'm using R.

    SRL> So I tried to run the professor's partreg.q file (attached to this
    SRL> message), and received this message:

    SRL> Error: couldn't find function "left.solve"

    SRL> The offending code is in line 62:

    SRL> Q_left.solve(R, cbind(rep(1,length(x)),x))

    SRL> Second bottom line (if such a thing is possible): how do I make
    SRL> this code work under R?  Is the cause hopeless?

Not at all :

Splus  help on   left.solve  says

>> USAGE:
>>        left.solve(r, x)
>> 
>>        This  is  support   for   the   functions   lm.hat()   and
>>        lm.influence().   It is not intended to be called directly
>>        by users.

I.e. your professor shouldn't have used it (;-)

Then in S-plus (3.4)  

> dump("left.solve","")

"left.solve"<-
function(r, x)
{
# this should really be done using DTRSL in Linpack
	x[] <- x %*% solve(r)
	x
}

	{you could have done this over the modem line (without X11..)}

If you add the above function definition to your *.q file (or a better place)
all should work.

And yes, I don't think we'd want this function in R...



Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO D10	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><
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