Phobos unit testing uncovers a CPU bug

[KennyTM~]

On Nov 27, 10 05:25, Simen kjaeraas wrote:
> Don <nospam at nospam.com> wrote:
>
>> The difference was discovered through the unit tests for the
>> mathematical Special Functions which will be included in the next
>> compiler release. Discovery of the discrepancy happened only because
>> of several features of D:
>>
>> - built-in unit tests (encourages tests to be run on many machines)
>>
>> - built-in code coverage (the tests include extreme cases, simply
>> because I was trying to increase the code coverage to high values)
>>
>> - D supports the hex format for floats. Without this feature, the
>> discrepancy would have been blamed on differences in the
>> floating-point conversion functions in the C standard library.
>>
>> This experience reinforces my belief that D is an excellent language
>> for scientific computing.
>
> This sounds like a great sales argument. Gives us some bragging rights. :p
>
>
>> Thanks to David Simcha and Dmitry Olshansky for help in tracking this
>> down.
>
> Great job!
>
> Now, which of the results is correct, and has AMD and Intel been informed?
>

Intel is correct.

   yl2x(0x1.0076fc5cc7933866p+40L, LN2)
    == log(9240117798188457011/8388608)
    == 0x1.bba4a9f774f49d0a64ac5666c969fd8ca8e...p+4
                          ^