Re: [boost] Help wanted: porting/testing the Math Toolkit to MacOS X

From: John Maddock (john_at_[hidden])
Date: 2007-08-31 12:45:45

Stjepan Rajko wrote:
> On 8/31/07, John Maddock <john_at_[hidden]> wrote:
>>
>> Looks like I quashed most of the problems, but still missed a few,
>> also looks like expl is inaccurate on that platform?  Can you check
>> what std::exp(-8072.0L) evaluates to: should be
>> 2.371057450122979885196291188186517859e-3506 according to
>> functions.wolfram.com.
>>
>
> It's:
>
> 2.371057450122979876482639519674937e-3506

OK that's about 33 eps, which seems to account for the bulk of the error in
this case: so that would appear to be why erfc and bessel_k are less
accurate on that platform.  Shame :-(

John.

P.S.  Are you able to test with Apple's 128-bit "double double" at all?  Or 
is than only on Mach systems?  Thanks.