On 5/15/2016 11:00 PM, Ola Fosheim Grøstad wrote:
On Sunday, 15 May 2016 at 22:49:27 UTC, Walter Bright wrote:
On 5/15/2016 2:06 PM, Ola Fosheim Grøstad wrote:
The net result is that adding const/immutable to a type can change the semantics
of the program entirely at the whim of the compiler implementor.
C++ Standard allows the same increased precision, at the whim of the compiler
implementor, as quoted to you earlier.
What your particular C++ compiler does is not relevant, as its behavior is not
required by the Standard.
This is a crazy attitude to take. C++ provides means to detect that IEEE floats
are being used in the standard library.
IEEE floats do not specify precision of intermediate results. A C/C++ compiler
can be fully IEEE compliant and yet legitimately have increased precision for
intermediate results.
I posted several links here pointing out this behavior in VC++ and g++. If your
C++ numerics code didn't have a problem with it, it's likely you wrote the code
in such a way that more accurate answers were not wrong.
FP behavior has complex trade-offs with speed, accuracy, compatibility, and
size. There are no easy, obvious answers.
