Speed of math function atan: comparison D and C++

[H. S. Teoh]

On Tue, Mar 06, 2018 at 08:12:57AM +0100, Robert M. Münch via Digitalmars-d-learn wrote:
> On 2018-03-05 20:11:06 +0000, H. S. Teoh said:
> 
> > Walter has been adamant that we should always compute std.math.*
> > functions with the `real` type, which on x86 maps to the non-IEEE
> > 80-bit floats.  However, 80-bit floats have been deprecated for a
> > while now,
> 
> Hi, do you have a reference for this? I can't believe this, as the
> 80-bit are pretty important for a lot of optimization algorithms. We
> use it all the time and it's absolutly necessary.
[...]

http://www.zdnet.com/article/nvidia-de-optimizes-physx-for-the-cpu/?tag=nl.e539

Quotation:

	Intel started discouraging the use of x87 with the introduction
	of the P4 in late 2000. AMD deprecated x87 since the K8 in 2003,
	as x86-64 is defined with SSE2 support; VIA’s C7 has supported
	SSE2 since 2005. In 64-bit versions of Windows, x87 is
	deprecated for user-mode, and prohibited entirely in
	kernel-mode. Pretty much everyone in the industry has
	recommended SSE over x87 since 2005 and there are no reasons to
	use x87, unless software has to run on an embedded Pentium or
	486. 

I'm not advocating for getting *rid* of 80-bit float support, but only
to make it *optional* rather than the default, as currently done in
std.math.


T

-- 
Once bitten, twice cry...