From maechler at stat.math.ethz.ch  Mon Apr 11 15:14:16 2016
From: maechler at stat.math.ethz.ch (Martin Maechler)
Date: Mon, 11 Apr 2016 15:14:16 +0200
Subject: [Rd] Optimization bug when byte compiling with gcc
	5.3.0	on	windows
In-Reply-To: <1460378536304.33286@jhu.edu>
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>>>>> Ravi Varadhan <ravi.varadhan at jhu.edu>
>>>>>     on Mon, 11 Apr 2016 12:42:35 +0000 writes:

    > all.equal.eigen() should also accommodate complex vectors, right?
    > Ravi

Yes, definitely.   The  ?eigen  help page does nicely mention
that in the complex the eigen vectors are even less determined,
i.e. you could multiply them by any unit length complex number
(of which only two are available in the real case:  +/- 1).

Martin

    > ________________________________________
    > From: R-devel <r-devel-bounces at r-project.org> on behalf of Martin Maechler <maechler at stat.math.ethz.ch>
    > Sent: Monday, April 11, 2016 3:08 AM
    > To: William Dunlap
    > Cc: r-devel; Jeroen Ooms
    > Subject: Re: [Rd] Optimization bug when byte compiling with gcc 5.3.0   on      windows

>>>>> William Dunlap via R-devel <r-devel at r-project.org>
>>>>>     on Mon, 4 Apr 2016 12:26:38 -0700 writes:

    >>> If I recall correctly, some eigen vectors had their
    >>> direction flipped (negative values became positive and
    >>> vice versa).  Did you notice anything of this kind when
    >>> running 'make check' and 'make check recommended' ? It is
    >>> important to us that numeric results are reproducible
    >>> between versions of R.

    >> I think that any code that depends on the direction of an
    >> eigenvector should be considered broken.

    > I agree [even though I may have fallen into that trap in some of
    > the regression tests I had written in the long past!].

    >> It is too bad that eigen's output does not have a class so
    >> that an all.equal method that know that the vector
    >> direction is not relevant could be written for it

    > That's an interesting / neat idea.
    > So we could give it S3 class "eigen"  iff  only.values is not
    > true, which would also "solve" the slightly differently
    > structured result of eigen()

    > Are you (or others) willing to provide a prototype for
    > all.equal.eigen ?

    > Martin

    >> Bill Dunlap TIBCO Software wdunlap tibco.com

    >> On Mon, Apr 4, 2016 at 11:39 AM, Jeroen Ooms
    >> <jeroen.ooms at stat.ucla.edu> wrote:

    >>> On Sun, Apr 3, 2016 at 6:44 PM, Ray Donnelly
    >>> <rdonnelly at continuum.io> wrote: > I've started to look
    >>> into building R for Windows using MSYS2 as both the >
    >>> build environment and tools + libraries provider (where
    >>> possible).
    >>> 
    >>> Thanks for your reply, and for the patches.
    >>> 
    >>> Last time I had a look at this (a few months ago) another
    >>> problem was that mingw-w64 v4 was giving different
    >>> numeric output for some of the tests in r-base. If I
    >>> recall correctly, some eigen vectors had their direction
    >>> flipped (negative values became positive and vice versa).
    >>> Did you notice anything of this kind when running 'make
    >>> check' and 'make check recommended' ? It is important to
    >>> us that numeric results are reproducible between versions
    >>> of R.



[Rd] Optimization bug when byte compiling with gcc 5.3.0 on windows
Martin Maechler