Re: [boost] C++ Standard Library proposal - Math functionsforStatistics

[Gabriel Dos Reis]

"Paul A. Bristow" <[EMAIL PROTECTED]> writes:

| Indeed, I doubt if long double is practically useful for many applications -
| even 16 decimal place 64-bit double will be impracticable on MSVC where there
| isn't really a long double (you may need to use 80-bit calculations to get a
| 64-bit accuracy result).
| 
| But I don't believe that this is a problem - exp, sin etc don't really work for
| long double on MSVC either! And many implementations are not fully accurate -
| nor would one necessarily want to wait while they calculate to full accuracy.
| 
| The Standard does not, and should not, make any requirements about accuracy,
| memory size or speed.
| 
| So I feel they are panicing a bit.

Being one of the persons who raised the accuracy issue, I think I have
to say why.

The proposed mathematical functions are not there just for selling
compilers. They are there to serve *practical* purposes.  If there is
no accuracy guarantee, they don't worth to have -- they are already so
specialized.  LIA  has already set framework for those things.  Any
serious proposal to include such specialized functions need to pay
attention to those things.

-- Gaby
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RE: [boost] C++ Standard Library proposal - Math functionsforStatistics

[Paul A. Bristow]

Indeed, I doubt if long double is practically useful for many applications -
even 16 decimal place 64-bit double will be impracticable on MSVC where there
isn't really a long double (you may need to use 80-bit calculations to get a
64-bit accuracy result).

But I don't believe that this is a problem - exp, sin etc don't really work for
long double on MSVC either! And many implementations are not fully accurate -
nor would one necessarily want to wait while they calculate to full accuracy.

The Standard does not, and should not, make any requirements about accuracy,
memory size or speed.

So I feel they are panicing a bit.

Paul

Paul A Bristow, Prizet Farmhouse, Kendal, Cumbria, LA8 8AB  UK
+44 1539 561830   Mobile +44 7714 33 02 04
Mobile mailto:[EMAIL PROTECTED]
mailto:[EMAIL PROTECTED]



| -Original Message-
| From: [EMAIL PROTECTED]
| [mailto:[EMAIL PROTECTED] Behalf Of Beman Dawes
| Sent: Wednesday, April 23, 2003 12:17 PM
| To: Boost mailing list
| Subject: RE: [boost] C++ Standard Library proposal - Math functions
| forStatistics
|
|
| At 04:21 AM 4/23/2003, Paul A. Bristow wrote:
|
|  >I feel Boost can also help by providing just one working implementation,
|  >even if just at 32-bit float accuracy, so any vendor who doesn't feel
|  >willing or able to provide a better one can still offer the Boost one
|  >and claim compliance.
|
| What worried the vendors wasn't the float accuracy, but the long double
| accuracy.
|
| One particular worry was that the amount of machine time required would be
| on the order of months.
|
| --Beman
|
|
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