From hm at student.ethz.ch  Wed Jun 14 03:28:38 2006
From: hm at student.ethz.ch (hm at student.ethz.ch)
Date: Wed, 14 Jun 2006 03:28:38 +0200 (CEST)
Subject: [Rd] Bug or not? (PR#8977)
Message-ID: <20060614012838.184FF29D44@slim.kubism.ku.dk>

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Hi,

I am writing this email, because I am not sure if the issue I have
discovered is a bug or not.

For a few days I have been fiddling around with a small program that
calculates the reflectance of multilayer dielectric mirrors (eg. bragg
mirrors). It does not really matter what I did, what matters is that I
could not do that using R.
I had some sample data which I used to test if my R program works
correctly (if it fits the data it works). This sample data was for two
different incident angles with respect to the normal of the hypothetical
bragg mirror (0=B0 and 70=B0). The plots for 0=B0 matched perfectly but t=
hose
for 70=B0 were quite a bit off. After trying out all sorts of things for
several days, I tried the same algorithm in octave (matlab clone, but
open source). There, I got a perfect match for both 0=B0 and 70=B0. I alm=
ost
could not believe it, R must have calculated wrong.

The R version I use at home at the moment is 2.2.1 on gentoo linux. I
also tried version 2.1.0 at my university (debian stable), both had the
same result.

I uploaded everything to reproduce this to

http://n.ethz.ch/student/homartin/r-vs-octave/

There, you can also find the .pdf file of the comparison of the
reference, the R output and the one from octave.

The calculations are quite complex, nevertheless, I would be very happy
to read your reply concerning this problem.

Thanks in advance, best Regards,
	Martin


--=20
Better to use medicines at the outset than at the last moment.


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[Rd] Bug or not? (PR#8977)
hm at student.ethz.ch