is D so slow?

Fawzi Mohamed fmohamed at
Mon Jun 16 08:36:28 PDT 2008

On 2008-06-16 16:40:16 +0200, Fawzi Mohamed <fmohamed at> said:

> On 2008-06-16 16:32:56 +0200, Fawzi Mohamed <fmohamed at> said:
>> On 2008-06-15 13:53:30 +0200, baleog <maccarka at> said:
>>> Thank you for your replies! I used malloc instead of new and run time 
>>> was about 1sec
>> But you probably did not understand why... and it seems that neither 
>> did others around here...
>> Indeed it is a subtle pitfall in which it is easy to fall.
>> When you benchmark
>> 1) print something depending on the result like the sum of everything 
>> (it is not the main issue in this case, but doing it would have 
>> probably shown the problem), so you can also have at least a tiny 
>> chance to notice if your algorithm is wrong
>> 2) NaNs
> ehm, sorry...
> You do initialize everything...
> ehm, never post without testing...
> Fawzi

I tested... and well I was actually right (I should have trusted my gut 
feeling a little more...)

NaN is the culprit.

check your algorithm (you initialize, backwards for some strange 
reason) just part of the arrays...
  xs[] = 1.0;
  ys[] = 2.0;
instead of your strange loops, solves everything...


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