[R] R-1.7.1 regression test failure on alphaev68-dec-osf5.1

[Jeff Lewis]

> -----Original Message-----
> From: Peter Dalgaard BSA [mailto:p.dalgaard at biostat.ku.dk] 
> Sent: Tuesday, June 24, 2003 1:20 PM
> To: Jeff Lewis
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] R-1.7.1 regression test failure on 
> alphaev68-dec-osf5.1
> 
> 
> "Jeff Lewis" <jlewis at genomecorp.com> writes:
> 
> > I'm attempting to compile and install R version 1.7.1 for 
> my statistical
> > geneticists.  It seems to compile correctly -- that is, it compiles
> > without errors -- but the regression test is failing in the 
> following
> > manner:
> > 
> > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> > > ## log
> > > stopifnot(all.equal(log(1:10), log(1:10, exp(1))))
> > > stopifnot(all.equal(log10(30), log(30, 10)))
> > > stopifnot(all.equal(log2(2^pi), 2^log2(pi)))
> > > stopifnot(Mod(pi - log(exp(pi*1i)) / 1i) < .Machine$double.eps)
> > Error: Mod(pi - log(exp(pi * (0+1i)))/(0+1i)) < 
> .Machine$double.eps is
> > not TRUE
> > Execution halted
> > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> > 
> > I'm compiling on Tru64UNIX 5.1A using DECs C and Fortran 
> compilers and
> > perl 5.6.0.  I found the above error in a file named
> > 'reg-tests-1.Rout.fail'.  Any help you can give me would be most
> > appreciated.
> 
> Well, it seems to be an accuracy issue, so the first question would be
> what the values on both sides of the equality are (just start up R and
> enter the expressions on te command line). You might have
> 
> 1) Completely wrong results in complex arithmetic 
> 2) Slightly less than optimal accuracy
> 3) An underestimated .Machine$double.eps
> 
> Case 2) seems most likely, but case 3) has been observed with buggy
> compilers that optimize calculations where they shouldn't.



Thanks for the quick response.  The two sides of the equality are
definately different.  Here's what I'm seeing

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> pi
[1] 3.141593

> 1i
[1] 0+1i

> pi*1i
[1] 0+3.141593i

> exp(pi*1i)
[1] -1+1.224647e-16i

> log(exp(pi*1i))
[1] 0+3.141593i

> log(exp(pi*1i)) / 1i

[1] 3.141593+0i

> pi - log(exp(pi*1i)) / 1i
[1] 4.440892e-16+0i

> Mod(pi - log(exp(pi*1i)) / 1i)
[1] 4.440892e-16

> .Machine$double.eps
[1] 2.220446e-16

> Mod(pi - log(exp(pi*1i)) / 1i) < .Machine$double.eps
[1] FALSE

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

I get the same thing from R 1.6.2, which I compiled about six months
ago.  Is there anything I can/should do to fix this?