Re: [gentoo-amd64] Possible Math Problem - Request For Verification

[Marc Joliet <marcec@gmx.de>]

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Am Sat, 25 Jun 2011 13:41:11 -0400
schrieb Frank Peters <frank.peters@comcast.net>:

> Hello,
>
[background information]

Huh, I was unaware that GNU (since they're the authors of GCC/GLIBC) ever had
problems in this area. Since I use my machine for numerical tasks, too, I was
interested in seeing whether I would see the same problem.

> The code will take several minutes to compile, execute, and complete.  While
> the test is running it will spit out its progress to stdout.  Upon completion
> a brief summary is given:
>
> UCBFAIL indicates problems!
> /tmp/fp-test-results/ccos_DP.output: ucbtest UCBFAIL in COS(X) at line 444 for generic
> /tmp/fp-test-results/clib_DP.output: ucbtest UCBFAIL in cabsd at line 701 for double
> /tmp/fp-test-results/clib_DP.output: ucbtest UCBFAIL in powd at line 701 for double
> /tmp/fp-test-results/clib_DP.output:UCBFAIL clib_DP.output , 25 out of 25 tests completed
> /tmp/fp-test-results/csin_DP.output: ucbtest UCBFAIL in SIN(X) at line 444 for generic
>
> only 11 out of 14 show UCBPASS!

I ran the tests without any modifications to ucbREADME/linux.sh and don't get
the cabsd failure:

    UCBFAIL indicates problems!
    /tmp/fp-test-results/ccos_DP.output: ucbtest UCBFAIL in COS(X) at line 444 for generic
    /tmp/fp-test-results/clib_DP.output: ucbtest UCBFAIL in powd at line 701 for double
    /tmp/fp-test-results/clib_DP.output:UCBFAIL clib_DP.output , 25 out of 25 tests completed
    /tmp/fp-test-results/csin_DP.output: ucbtest UCBFAIL in SIN(X) at line 444 for generic

    only 11 out of 14 show UCBPASS!

Out of curiosity, I ran the test two more times and got the same results.

This machine runs on stable, with a slightly older Athlon64 X2.

> There are expected failures in the trigonometric tests since trigonometric
> performance is not specified in IEEE754/854.  The failure in powd (double power
> function) is also expected.  But everything else should have passed.

Then according to the results above my machine is apparently OK. (I guess I
really should finally read about IEEE floating point more thoroughly, I've been
planning to do that for a while now.)

[...]
> Frank Peters

HTH
-- 
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup

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