std.math performance (SSE vs. real)

[John Colvin via Digitalmars-d]

On Saturday, 28 June 2014 at 06:16:51 UTC, Walter Bright wrote:
> On 6/27/2014 10:18 PM, Walter Bright wrote:
>> On 6/27/2014 4:10 AM, John Colvin wrote:
>>> *The number of algorithms that are both numerically 
>>> stable/correct and benefit
>>> significantly from > 64bit doubles is very small.
>>
>> To be blunt, baloney. I ran into these problems ALL THE TIME 
>> when doing
>> professional numerical work.
>>
>
> Sorry for being so abrupt. FP is important to me - it's not 
> just about performance, it's also about accuracy.

I still maintain that the need for the precision of 80bit reals 
is a niche demand. Its a very important niche, but it doesn't 
justify having its relatively extreme requirements be the 
default. Someone writing a matrix inversion has only themselves 
to blame if they don't know plenty of numerical analysis and look 
very carefully at the specifications of all operations they are 
using.

Paying the cost of moving to/from the fpu, missing out on 
increasingly large SIMD units, these make everyone pay the price.

inclusion of the 'real' type in D was a great idea, but std.math 
should be overloaded for float/double/real so people have the 
choice where they stand on the performance/precision front.