Real Close to the Machine: Floating Point in D

[Lars T. Kyllingstad]

Don wrote:
> Lu’ís Marques wrote:
>>> A naive binary chop doesn't work correctly. The fact that there are 
>>> hundreds or thousands of times as many representable numbers between 
>>> 0 and 1, as there are between 1 and 2, is problematic for 
>>> divide-and-conquer algorithms. A naive binary chop would divide the 
>>> interval [0 .. 2] into [0 .. 1] and [1 .. 2]. Unfortunately, this is 
>>> not a true binary chop, because the interval [0 .. 1] contains more 
>>> than 99% of the representable numbers from the original interval!
>>
>> How about adding a template to do a binary chop (binary search?) to 
>> std.algorithm?
> 
> findRoot() (which needs to be updated to take advantage of compiler 
> improvements) does the job in the most important case. I'm quite proud 
> of it; as far as I know, it's uses a better algorithm than anything else 
> on the planet. <g>


Awesome! I hadn't even noticed the std.numeric module before. :)

Just a small comment: I think that the type of the function parameter 
should be templated as well, so that one can pass both functions, 
delegates and functors to it.

Just now I tried to apply findRoot to an actual problem I'm working on, 
and immediately failed because I tried to pass a free function to it. A 
trivial thing to work around, but annoying nevertheless.

How do you choose/limit what to put in std.numeric? I don't suppose 
you're going to put all of NETLIB in there... ;) Already, it seems to me 
that findRoot is somewhat niche for a standard library.


-Lars