Re: [boost] [serialization] Serialisation/deserialisation offloating-point values

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2006-03-17 06:18:53

Ooops - this is a typo.

It should of course be 3010/10000.

(All this is because floating point calculations, especially log10(2) =
0.3010.... can't be done at compile time - a shame because it could be - and
has received some consideration for the next C++0x).

Sorry.

Paul 

| -----Original Message-----
| From: boost-bounces_at_[hidden] 
| [mailto:boost-bounces_at_[hidden]] On Behalf Of Peter Broadwell
| Sent: 15 March 2006 20:43
| To: boost_at_[hidden]
| Subject: Re: [boost] [serialization] 
| Serialisation/deserialisation offloating-point values
| 
| Note the difference between the "definition" formulae of 3010/10000
| and the suggested formulae using 3030/10000.
| 
| Perhaps this is on purpose, if not may explain why the tests done
| later in this thread  wich use the 3030/10000 version had troubles?
| 
| ;;peter
| 
| 
| Paul A Bristow wrote:
|  > [...]
|  > For C++, using numeric limits,
|  >
|  > So it is convenient instead to use the following formula 
| which can be
|  > calculated at compile time:
|  > 2 + std::numeric_limits<double>::digits * 3010/10000;
|  >
|  > [...]
|  > and I suggest that this should be:
|  >
|  > os << std::setprecision(2 + std::numeric_limits<double>::digits *
|  > 3030/10000);
|  >
|  > HTH
|  >
|  > Paul
|  >
|  >
|  >
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