Floating Point + Threads?

[Fawzi Mohamed]

On 16-apr-11, at 09:41, Walter Bright wrote:

> On 4/15/2011 8:40 PM, Andrei Alexandrescu wrote:
>> On 4/15/11 10:22 PM, dsimcha wrote:
>>> I'm trying to debug an extremely strange bug whose symptoms appear  
>>> in a
>>> std.parallelism example, though I'm not at all sure the root cause  
>>> is in
>>> std.parallelism. The bug report is at
>>> https://github.com/dsimcha/std.parallelism/issues/ 
>>> 1#issuecomment-1011717 .
>>
>> Does the scheduling affect the summation order?
>
> That's a good thought. FP addition results can differ dramatically  
> depending on associativity.

yes, one can avoid this by using a tree algorithm with a fixed  
blocksize, then the results will be the same bothe in single and  
parallel case.
Normally one uses atomic sumation though.
In blip I spent quite a bit of thought on tree like algorithms and  
their parallelization exactly because the parallelize well and are  
independent form the paralleization

Fawzi