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Re: libm-test.inc: Computing ulps near FP_ZERO.
- From: Brooks Moses <brooks at codesourcery dot com>
- To: Carlos O'Donell <carlos at redhat dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, "Joseph S. Myers" <joseph at codesourcery dot com>, Andreas Jaeger <aj at suse dot com>, Thomas Schwinge <thomas at codesourcery dot com>, David Miller <davem at davemloft dot net>
- Date: Mon, 8 Apr 2013 18:04:18 -0700
- Subject: Re: libm-test.inc: Computing ulps near FP_ZERO.
- References: <51606D8A dot 9080003 at redhat dot com> <5160A4D7 dot 9080802 at codesourcery dot com> <516183BD dot 6060700 at redhat dot com> <5161AADF dot 2040403 at codesourcery dot com> <5161FA1A dot 5060100 at redhat dot com> <51620F35 dot 5080101 at codesourcery dot com> <51634CA1 dot 4050006 at redhat dot com>
Carlos O'Donell wrote, at 4/8/2013 4:02 PM:
> Regenerating ULPs for /home/carlos/build/glibc/math/test-idouble
> testing double (inline functions)
> Failure: Test: cos (pi/2) == PI_ERROR/2
> Result:
> is: 6.12323399573676603587e-17 0x1.1a62633145c070000000p-54
> should be: 1.11022302462515654042e-16 0x1.00000000000000000000p-53
> difference: 4.97899625051479936837e-17 0x1.cb3b399d747f20000000p-55
> ulp(x) : 2.46519032881566189191e-32 0x1.00000000000000000000p-105
> ulp : 2019720827359740.5000
> max.ulp : 0.0000
I think you've missed the bit where I pointed out that the expected
result here is "0 +/- ulp(pi/2)/2", not "ulp(pi/2)/2"!
In other words, you've confused the expected error bound with the
expected result.
- Brooks