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Re: Log2 and beta test failures
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From: |
Michael Goffioul |
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Subject: |
Re: Log2 and beta test failures |
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Date: |
Tue, 6 May 2008 10:05:37 +0200 |
On Tue, May 6, 2008 at 8:35 AM, Jaroslav Hajek <address@hidden> wrote:
> I don't have other g++ versions or compilers to try. Ben, Michael, can
> you try this fragment with your configurations? I don't see any
> obvious bug in the xlog2 mappers, so I guess this may be the cause.
On MSVC, I get (0,inf) whatever the optimization level. I did the same
with cygwin gcc-3.4.4 and it gave me (nan,inf) whatever the optimization
level.
However, the test failures I reported are not related to that, but
to the second form of xlog2:
double xlog2(double x, int& exp)
when x = Inf. This results in a call to frexp with infinite value.
I tested it under MSVC and I got:
frexp(Inf) => NaN, -1
but from the test code in src/data.cc, it seems the expected
values are
frexp(Inf) => Inf, 0
Michael.