[Boost-commit] svn:boost r83662 - sandbox/precision/libs/precision/doc

Subject: [Boost-commit] svn:boost r83662 - sandbox/precision/libs/precision/doc
From: e_float_at_[hidden]
Date: 2013-03-31 08:22:21

Author: christopher_kormanyos
Date: 2013-03-31 08:22:21 EDT (Sun, 31 Mar 2013)
New Revision: 83662
URL: http://svn.boost.org/trac/boost/changeset/83662

Log:
Further improvements of clarity. Added comments about endianness.
Text files modified: 
   sandbox/precision/libs/precision/doc/precision.qbk |    33 +++++++++++++++++----------------       
   1 files changed, 17 insertions(+), 16 deletions(-)

Modified: sandbox/precision/libs/precision/doc/precision.qbk
==============================================================================
--- sandbox/precision/libs/precision/doc/precision.qbk	(original)
+++ sandbox/precision/libs/precision/doc/precision.qbk	2013-03-31 08:22:21 EDT (Sun, 31 Mar 2013)
@@ -125,11 +125,6 @@
 [*This situation reveals a need for a standard way to specify
 floating-point precision in C++.]
 
-It may also be desirable to extend floating-point precision to
-both lower and higher precisions. This can be done by including
-implementation-specific `typedef`s having specified widths
-that are not derived from `float`, `double`, and `long double`.
-
 Providing optional floating-point `typedef`s having specified widths
 is expected to significantly improve portability, reliability, and safety
 of floating-point calculations in C++.
@@ -141,13 +136,12 @@
 
 [section:thetypedefs  The proposed typedefs and potential extensions]
 
-The core of this proposal is based on the
-optional floating-point `typedef`s `float16_t`, `float32_t`,
-`float64_t`, `float128_t`,
+The core of this proposal is based on the optional floating-point
+`typedef`s `float16_t`, `float32_t`, `float64_t`, `float128_t`,
 their corresponding least and fast types,
 and the corresponding maximum-width type.
 
-For example,
+In particular,
 
   // Sample partial synopsis of <cstdfloat>
 
@@ -203,18 +197,25 @@
 
 No matter what naming scheme is used, the exact layout and number of significand
 and exponent bits can be confirmed as IEEE754 by checking
-`std::numeric_limits<type>::is_iec559 == true`, and the byte-order.
+`std::numeric_limits<type>::is_iec559 == true`, and the byte order.
 
 [note __IEEE_floating_point prescribes a method of precision extension,
 that allows for conforming types other than `binary16`, `binary32`, `binary64`, and `binary128`.
-Furthermore, paragraph 3.7 in __IEEE_floating_point states:
+This makes it possible to extend floating-point precision to both lower and higher precisions
+in a standardized way using implementation-specific `typedef`s
+that are not derived from `float`, `double`, and `long double`.]
+
+[note Paragraph 3.7 in __IEEE_floating_point states:
 [*Language standards should define mechanisms supporting extendable precision
 for each supported radix]. This proposal embodies a potential way for
 C++ to adhere to this requirement.]
 
-We will now consider several examples showing how
-various implementations might introduce some of the
-optional floating-point `typedef`s having specified widths
+[note __IEEE_floating_point does not specify the byte order for floating-point
+storage (the so-called endianness). This is the same situation that prevails for
+integer storage in C++.]
+
+We will now consider various examples that show how implementations might introduce
+some of the optional floating-point `typedef`s having specified widths
 into the `std` namespace.
 
 An implementation has `float` and `double` corresponding to
@@ -241,7 +242,7 @@
 Consider an implementation for a supercomputer. This platform has
 `float`, `double`, and `long double` corresponding to IEEE754
 `binary32`, `binary64`, and `binary128`, respectively. In addition, this
-platform has floating-point types with octuple-precision and hextuple-precision.
+implementation has floating-point types with octuple-precision and hextuple-precision.
 The implementation for this supercomputer could introduce
 its optional floating-point `typedef`s having specified widths
 into the `std` namespace as shown below.
@@ -342,7 +343,7 @@
   #include <cstdfloat>
 
   static_assert(FLOATMAX_MAX > (std::numeric_limits<float>::max)(),
-                "The floating-point range is too small.");
+                "The iec559 floating-point range is too small.");
 
 [endsect] [/section:literals Handling floating-point literals]